refactor: централизация всех расчётов цен в PricingEngine

- Мигрирован confirm_purchase() на calculate_classic_new_subscription_price()
- Мигрирован compute_simple_subscription_price на делегацию в PricingEngine
- Мигрирован handle_custom_confirm на calculate_tariff_purchase_price()
- Мигрированы daily confirm handlers (confirm_daily_tariff_purchase,
  confirm_daily_tariff_switch, confirm_instant_switch daily path)
- Мигрирован gift.py на calculate_tariff_purchase_price()
- Мигрированы FSM cache prices (select_period, select_devices, toggle_country)
- Добавлен lock_user_for_pricing в admin_buy_tariff_execute (TOCTOU fix)
- Добавлен lock + recompute в _auto_add_devices и _auto_add_traffic
- Исправлено двойное применение promo-offer в simple_subscription (критический баг)
- Унифицирован daily price display (group+offer) на всех 6 поверхностях
- PricingEngine.get_addon_discount_percent: добавлен promo_group= kwarg
- PricingEngine._calculate_switch_to/from_daily: добавлен promo-offer discount
- Удалён мёртвый код из common.py (_get_addon_discount_percent_for_user)
- Miniapp period_discounts: исправлен доступ через get_discount_percent()

app/cabinet/routes/gift.py

@@ -22,7 +22,6 @@ from app.database.models import (
     Tariff,
     TransactionType,
     User,
-    UserPromoGroup,
 )
 from app.services.guest_purchase_service import (
     GuestPurchaseError,
@@ -112,15 +111,17 @@ async def get_gift_config(
             price = base_price
 
             # Apply promo group discount
+            from app.services.pricing_engine import PricingEngine
+
             promo_group_discount = 0
             if promo_group:
                 promo_group_discount = promo_group.get_discount_percent('period', days)
                 if promo_group_discount > 0:
-                    price = int(price * (100 - promo_group_discount) / 100)
+                    price = PricingEngine.apply_discount(price, promo_group_discount)
 
             # Apply active promo offer discount (stacks on top)
             if promo_offer_discount_percent > 0:
-                price = price - price * promo_offer_discount_percent // 100
+                price = PricingEngine.apply_discount(price, promo_offer_discount_percent)
 
             # Ensure minimum price of 1 kopek after all discounts
             price = max(1, price)
@@ -249,43 +250,28 @@ async def create_gift_purchase(
             detail='Tariff not found or inactive',
         )
 
-    price_kopeks = tariff.get_price_for_period(body.period_days)
-    if price_kopeks is None:
+    # Validate that period has a configured price before locking
+    if tariff.get_price_for_period(body.period_days) is None:
         raise HTTPException(
             status_code=status.HTTP_400_BAD_REQUEST,
             detail='Price is not configured for this period',
         )
 
-    # Lock user row to prevent concurrent promo offer double-spend
-    locked_result = await db.execute(
-        select(User)
-        .options(
-            selectinload(User.user_promo_groups).selectinload(UserPromoGroup.promo_group),
-            selectinload(User.promo_group),
-        )
-        .where(User.id == user.id)
-        .with_for_update()
-        .execution_options(populate_existing=True)
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
+    from app.services.pricing_engine import pricing_engine
+
+    pricing_result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        body.period_days,
+        device_limit=tariff.device_limit,
+        user=user,
     )
-    user = locked_result.scalar_one()
-
-    # Apply promo group discount
-    promo_group = user.get_primary_promo_group() if hasattr(user, 'get_primary_promo_group') else None
-    if promo_group is None:
-        promo_group = getattr(user, 'promo_group', None)
-
-    if promo_group:
-        discount_percent = promo_group.get_discount_percent('period', body.period_days)
-        if discount_percent > 0:
-            price_kopeks = int(price_kopeks * (100 - discount_percent) / 100)
-
-    # Apply active promo offer discount (stacks)
-    promo_offer_discount_percent = get_user_active_promo_discount_percent(user)
-    if promo_offer_discount_percent > 0:
-        price_kopeks = price_kopeks - price_kopeks * promo_offer_discount_percent // 100
-
-    # Ensure minimum price of 1 kopek after all discounts
-    price_kopeks = max(1, price_kopeks)
+    price_kopeks = max(1, pricing_result.final_total)
+    consume_promo = pricing_result.promo_offer_discount > 0
 
     # Determine buyer contact info
     if user.email:
@@ -420,7 +406,7 @@ async def create_gift_purchase(
             )
 
         # Consume promo offer discount before committing gateway purchase
-        if promo_offer_discount_percent > 0 and getattr(user, 'promo_offer_discount_percent', 0):
+        if consume_promo and getattr(user, 'promo_offer_discount_percent', 0):
             user.promo_offer_discount_percent = 0
             user.promo_offer_discount_source = None
             user.promo_offer_discount_expires_at = None
@@ -485,7 +471,7 @@ async def create_gift_purchase(
         price_kopeks,
         description=f'Gift: {tariff.name} ({body.period_days}d)',
         create_transaction=False,
-        consume_promo_offer=promo_offer_discount_percent > 0,
+        consume_promo_offer=consume_promo,
     )
     if not balance_ok:
         await db.rollback()

app/cabinet/routes/landing.py

@@ -342,7 +342,9 @@ async def _load_landing_tariffs(
                 effective_discount = tariff_override if tariff_override is not None else discount.percent
                 original_price_kopeks = price
                 original_price_label = settings.format_price(price)
-                price = max(1, price - (price * effective_discount // 100))
+                from app.services.pricing_engine import PricingEngine
+
+                price = max(1, PricingEngine.apply_discount(price, effective_discount))
 
             periods.append(
                 LandingTariffPeriod(

app/cabinet/routes/subscription.py

@@ -42,7 +42,6 @@ from app.services.system_settings_service import bot_configuration_service
 from app.services.user_cart_service import user_cart_service
 from app.utils.cache import RateLimitCache, cache, cache_key
 from app.utils.pricing_utils import format_period_description
-from app.utils.promo_offer import get_user_active_promo_discount_percent
 
 from ..dependencies import get_cabinet_db, get_current_cabinet_user
 from ..schemas.subscription import (
@@ -68,29 +67,14 @@ router = APIRouter(prefix='/subscription', tags=['Cabinet Subscription'])
 
 
 def _get_addon_discount_percent(
-    user: User,
+    user: User | None,
     category: str,
-    period_days: int | None = None,
+    period_days_hint: int | None = None,
 ) -> int:
-    """Get addon discount percent for user from promo group.
+    """Get addon discount percent for user — delegates to PricingEngine."""
+    from app.services.pricing_engine import PricingEngine
 
-    Mirrors logic from app/handlers/subscription/common.py:_get_addon_discount_percent_for_user
-    """
-    promo_group = (
-        user.get_primary_promo_group()
-        if hasattr(user, 'get_primary_promo_group')
-        else getattr(user, 'promo_group', None)
-    )
-    if promo_group is None:
-        return 0
-
-    if not getattr(promo_group, 'apply_discounts_to_addons', True):
-        return 0
-
-    try:
-        return user.get_promo_discount(category, period_days)
-    except AttributeError:
-        return 0
+    return PricingEngine.get_addon_discount_percent(user, category, period_days_hint)
 
 
 def _apply_addon_discount(
@@ -117,27 +101,12 @@ def _apply_addon_discount(
     }
 
 
-def _get_period_discount_percent(user: User, period_days: int | None = None) -> int:
-    """Get period discount percent for tariff switch calculations."""
-    promo_group = (
-        user.get_primary_promo_group()
-        if hasattr(user, 'get_primary_promo_group')
-        else getattr(user, 'promo_group', None)
-    )
-    if promo_group is None:
-        return 0
-
-    try:
-        return user.get_promo_discount('period', period_days)
-    except AttributeError:
-        return 0
-
-
 def _subscription_to_response(
     subscription: Subscription,
     servers: list[ServerInfo] | None = None,
     tariff_name: str | None = None,
     traffic_purchases: list[dict[str, Any]] | None = None,
+    user: User | None = None,
 ) -> SubscriptionData:
     """Convert Subscription model to response."""
     now = datetime.now(UTC)
@@ -200,6 +169,18 @@ def _subscription_to_response(
     traffic_reset_mode = None
     if tariff_id and hasattr(subscription, 'tariff') and subscription.tariff:
         daily_price_kopeks = getattr(subscription.tariff, 'daily_price_kopeks', None)
+        # Применяем скидку промогруппы + promo-offer для отображения
+        if daily_price_kopeks and daily_price_kopeks > 0 and user:
+            from app.services.pricing_engine import PricingEngine
+            from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+            _promo_group = user.get_primary_promo_group() if hasattr(user, 'get_primary_promo_group') else None
+            _group_pct = _promo_group.get_discount_percent('period', 1) if _promo_group else 0
+            _offer_pct = get_user_active_promo_discount_percent(user)
+            if _group_pct > 0 or _offer_pct > 0:
+                daily_price_kopeks, _, _ = PricingEngine.apply_stacked_discounts(
+                    daily_price_kopeks, _group_pct, _offer_pct
+                )
         if not tariff_name:  # Only set if not passed as parameter
             tariff_name = getattr(subscription.tariff, 'name', None)
         traffic_reset_mode = (
@@ -321,7 +302,9 @@ async def get_subscription(
             }
         )
 
-    subscription_data = _subscription_to_response(fresh_user.subscription, servers, tariff_name, traffic_purchases_data)
+    subscription_data = _subscription_to_response(
+        fresh_user.subscription, servers, tariff_name, traffic_purchases_data, user=fresh_user
+    )
     return SubscriptionStatusResponse(has_subscription=True, subscription=subscription_data)
 
 
@@ -401,6 +384,11 @@ async def renew_subscription(
             detail='Selected renewal period is not available',
         )
 
+    # Lock user row to prevent TOCTOU on promo-offer state
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     # Unified pricing via PricingEngine
     pricing = await pricing_engine.calculate_renewal_price(
         db,
@@ -724,6 +712,11 @@ async def purchase_traffic(
             subscription.end_date,
         )
 
+    # Lock user row to prevent TOCTOU on promo-offer state
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     # Apply discount from promo group using proper method
     period_hint_days = days_charged if days_charged > 0 else 30
     discount_result = _apply_addon_discount(user, 'traffic', prorated_price, period_hint_days)
@@ -923,6 +916,11 @@ async def purchase_devices_legacy(
 
     base_total_price = device_price * request.devices
 
+    # Lock user row to prevent TOCTOU on promo-offer state
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     # Apply discount from promo group
     discount_result = _apply_addon_discount(user, 'devices', base_total_price, 30)
     total_price = discount_result['discounted']
@@ -1363,7 +1361,7 @@ async def activate_trial(
     except Exception as e:
         logger.error('Failed to send trial activation notification', error=e)
 
-    return _subscription_to_response(subscription)
+    return _subscription_to_response(subscription, user=user)
 
 
 # ============ Full Purchase Flow (like MiniApp) ============
@@ -1427,17 +1425,29 @@ async def _build_tariff_response(
             # Стоимость доп. устройств за этот период
             extra_devices_cost = extra_devices_count * extra_device_price_per_month * months
 
-            # Apply promo group discount for this period (на базовую цену тарифа)
+            # Apply per-category promo group discounts
             original_price = base_tariff_price + extra_devices_cost
-            discount_percent = 0
             discount_amount = 0
-            final_price = original_price
 
             if promo_group:
-                discount_percent = promo_group.get_discount_percent('period', period_days)
-                if discount_percent > 0:
-                    discount_amount = original_price * discount_percent // 100
-                    final_price = original_price - discount_amount
+                period_pct = promo_group.get_discount_percent('period', period_days)
+                devices_pct = promo_group.get_discount_percent('devices', period_days)
+                discounted_base = (
+                    pricing_engine.apply_discount(base_tariff_price, period_pct)
+                    if period_pct > 0
+                    else base_tariff_price
+                )
+                discounted_devices = (
+                    pricing_engine.apply_discount(extra_devices_cost, devices_pct)
+                    if devices_pct > 0
+                    else extra_devices_cost
+                )
+                final_price = discounted_base + discounted_devices
+                discount_amount = original_price - final_price
+                discount_percent = max(period_pct, devices_pct)
+            else:
+                discount_percent = 0
+                final_price = original_price
 
             per_month = final_price // months if months > 0 else final_price
             original_per_month = original_price // months if months > 0 else original_price
@@ -1474,16 +1484,21 @@ async def _build_tariff_response(
 
     traffic_label = '♾️ Безлимит' if tariff.traffic_limit_gb == 0 else f'{tariff.traffic_limit_gb} ГБ'
 
-    # Apply discount to daily price if applicable
+    # Apply discount to daily price if applicable (group + promo-offer)
     daily_price = getattr(tariff, 'daily_price_kopeks', 0)
     original_daily_price = daily_price
     daily_discount_percent = 0
-    if promo_group and daily_price > 0:
-        # For daily tariffs, use period discount with period_days=1
-        daily_discount_percent = promo_group.get_discount_percent('period', 1)
-        if daily_discount_percent > 0:
-            discount_amount = daily_price * daily_discount_percent // 100
-            daily_price = daily_price - discount_amount
+    if daily_price > 0:
+        from app.services.pricing_engine import PricingEngine
+        from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+        daily_group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+        daily_offer_pct = get_user_active_promo_discount_percent(user) if user else 0
+        if daily_group_pct > 0 or daily_offer_pct > 0:
+            daily_price, _, _ = PricingEngine.apply_stacked_discounts(daily_price, daily_group_pct, daily_offer_pct)
+            # Комбинированный процент для отображения
+            remaining = (100 - daily_group_pct) * (100 - daily_offer_pct)
+            daily_discount_percent = 100 - remaining // 100
 
     # Apply discount to custom price_per_day if applicable
     price_per_day = tariff.price_per_day_kopeks
@@ -1492,18 +1507,16 @@ async def _build_tariff_response(
     if promo_group and price_per_day > 0:
         custom_days_discount_percent = promo_group.get_discount_percent('period', 30)  # Use 30-day rate as base
         if custom_days_discount_percent > 0:
-            discount_amount = price_per_day * custom_days_discount_percent // 100
-            price_per_day = price_per_day - discount_amount
+            price_per_day = pricing_engine.apply_discount(price_per_day, custom_days_discount_percent)
 
     # Apply discount to device price if applicable
     device_price = tariff.device_price_kopeks if tariff.device_price_kopeks is not None else 0
     original_device_price = device_price
     device_discount_percent = 0
     if promo_group and device_price > 0:
-        device_discount_percent = promo_group.get_discount_percent('devices')
+        device_discount_percent = promo_group.get_discount_percent('devices', 30)
         if device_discount_percent > 0:
-            discount_amount = device_price * device_discount_percent // 100
-            device_price = device_price - discount_amount
+            device_price = pricing_engine.apply_discount(device_price, device_discount_percent)
 
     # Показываем реальное количество устройств (с докупленными) для текущего тарифа
     actual_device_limit = tariff.device_limit
@@ -1703,6 +1716,9 @@ async def submit_purchase(
         )
 
     try:
+        from app.database.crud.user import lock_user_for_pricing
+
+        user = await lock_user_for_pricing(db, user.id)
         context = await purchase_service.build_options(db, user)
 
         # Convert request to dict for parsing
@@ -1774,7 +1790,7 @@ async def submit_purchase(
         return {
             'success': True,
             'message': result['message'],
-            'subscription': _subscription_to_response(subscription),
+            'subscription': _subscription_to_response(subscription, user=user),
             'was_trial_conversion': result.get('was_trial_conversion', False),
         }
 
@@ -1854,6 +1870,11 @@ async def purchase_tariff(
                 detail='Tariff not found or inactive',
             )
 
+        # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+        from app.database.crud.user import lock_user_for_pricing
+
+        user = await lock_user_for_pricing(db, user.id)
+
         # Check tariff availability for user's promo group and get promo group for discounts
         promo_group = user.get_primary_promo_group() if hasattr(user, 'get_primary_promo_group') else None
         promo_group_id = promo_group.id if promo_group else None
@@ -1865,105 +1886,43 @@ async def purchase_tariff(
 
         # Handle daily tariffs specially
         is_daily_tariff = getattr(tariff, 'is_daily', False)
-        discount_percent = 0
-        original_price = 0
-
         if is_daily_tariff:
-            daily_price = getattr(tariff, 'daily_price_kopeks', 0)
-            if daily_price <= 0:
-                raise HTTPException(
-                    status_code=status.HTTP_400_BAD_REQUEST,
-                    detail='Daily tariff has invalid price',
-                )
-            original_price = daily_price
-            # Apply promo group discount for daily tariff
-            if promo_group:
-                discount_percent = promo_group.get_discount_percent('period', 1)
-                if discount_percent > 0:
-                    discount_amount = daily_price * discount_percent // 100
-                    daily_price = daily_price - discount_amount
-            # For daily tariffs, charge first day and set period to 1 day
-            price_kopeks = daily_price
             period_days = 1
         else:
             period_days = request.period_days
-            # Get price for period (support custom days)
-            price_kopeks = tariff.get_price_for_period(period_days)
-            if price_kopeks is None:
-                # Check for custom days
-                if tariff.can_purchase_custom_days():
-                    price_kopeks = tariff.get_price_for_custom_days(period_days)
-                    if price_kopeks is None:
-                        raise HTTPException(
-                            status_code=status.HTTP_400_BAD_REQUEST,
-                            detail=f'Period must be between {tariff.min_days} and {tariff.max_days} days',
-                        )
-                else:
-                    raise HTTPException(
-                        status_code=status.HTTP_400_BAD_REQUEST,
-                        detail='Invalid period for this tariff',
-                    )
 
-            original_price = price_kopeks
-            # Apply promo group discount for period
-            if promo_group and price_kopeks > 0:
-                discount_percent = promo_group.get_discount_percent('period', period_days)
-                if discount_percent > 0:
-                    discount_amount = price_kopeks * discount_percent // 100
-                    price_kopeks = price_kopeks - discount_amount
-
-        # Calculate traffic limit and price
+        # Determine traffic limit (custom traffic support)
         traffic_limit_gb = tariff.traffic_limit_gb
-        traffic_price_kopeks = 0
+        custom_traffic_gb = None
         if request.traffic_gb is not None and tariff.can_purchase_custom_traffic():
-            # Custom traffic requested
-            traffic_price_kopeks = tariff.get_price_for_custom_traffic(request.traffic_gb)
-            if traffic_price_kopeks is None:
-                raise HTTPException(
-                    status_code=status.HTTP_400_BAD_REQUEST,
-                    detail=f'Traffic must be between {tariff.min_traffic_gb} and {tariff.max_traffic_gb} GB',
-                )
-            # Apply traffic discount if promo group has it
-            if promo_group and traffic_price_kopeks > 0:
-                traffic_discount_percent = promo_group.get_discount_percent('traffic', period_days)
-                if traffic_discount_percent > 0:
-                    traffic_discount = traffic_price_kopeks * traffic_discount_percent // 100
-                    traffic_price_kopeks = traffic_price_kopeks - traffic_discount
+            custom_traffic_gb = request.traffic_gb
             traffic_limit_gb = request.traffic_gb
-            price_kopeks += traffic_price_kopeks
 
-        # Проверяем, есть ли докупленные устройства при продлении того же тарифа
+        # Determine device_limit for renewal pricing
         existing_subscription = await get_subscription_by_user_id(db, user.id)
-        extra_devices = 0
+        device_limit = None
         effective_device_limit = tariff.device_limit
         if existing_subscription and existing_subscription.tariff_id == tariff.id:
-            extra_devices = max(0, (existing_subscription.device_limit or 0) - (tariff.device_limit or 0))
-            if extra_devices > 0:
+            device_limit = existing_subscription.device_limit
+            if (existing_subscription.device_limit or 0) > (tariff.device_limit or 0):
                 effective_device_limit = existing_subscription.device_limit
-                if not is_daily_tariff:
-                    from app.utils.pricing_utils import calculate_months_from_days
 
-                    device_price_per_month = (
-                        tariff.device_price_kopeks
-                        if tariff.device_price_kopeks is not None
-                        else settings.PRICE_PER_DEVICE
-                    )
-                    months = calculate_months_from_days(period_days)
-                    extra_devices_cost = extra_devices * device_price_per_month * months
-                    # Применяем скидку промогруппы на устройства
-                    if promo_group and extra_devices_cost > 0:
-                        devices_discount_pct = promo_group.get_discount_percent('devices', period_days)
-                        if devices_discount_pct > 0:
-                            extra_devices_cost = extra_devices_cost - (extra_devices_cost * devices_discount_pct // 100)
-                    price_kopeks += extra_devices_cost
-
-        # Apply promo offer discount (temporary discount from promo offers)
-        price_before_promo_offer = price_kopeks
-        promo_offer_discount_percent = get_user_active_promo_discount_percent(user)
-        promo_offer_discount_value = 0
-        if promo_offer_discount_percent > 0:
-            promo_offer_discount_value = price_kopeks * promo_offer_discount_percent // 100
-            price_kopeks = price_kopeks - promo_offer_discount_value
+        # Calculate price via PricingEngine (single source of truth)
+        result = await pricing_engine.calculate_tariff_purchase_price(
+            tariff,
+            period_days,
+            device_limit=device_limit,
+            custom_traffic_gb=custom_traffic_gb,
+            user=user,
+        )
+        price_kopeks = result.final_total
+        original_price = result.original_total
+        bd = result.breakdown
+        group_pcts = bd.get('group_discount_pct', {})
+        discount_percent = group_pcts.get('period', 0)
+        promo_offer_discount_percent = bd.get('offer_discount_pct', 0)
+        promo_offer_discount_value = result.promo_offer_discount
+        price_before_promo_offer = price_kopeks + promo_offer_discount_value
 
         # Check balance
         if user.balance_kopeks < price_kopeks:
@@ -2141,7 +2100,7 @@ async def purchase_tariff(
         response = {
             'success': True,
             'message': f"Тариф '{tariff.name}' успешно активирован",
-            'subscription': _subscription_to_response(subscription),
+            'subscription': _subscription_to_response(subscription, user=user),
             'tariff_id': tariff.id,
             'tariff_name': tariff.name,
             'charged_amount': price_kopeks,
@@ -2319,6 +2278,11 @@ async def purchase_devices(
         base_price_prorated = int(base_price_per_month * days_left / total_days)
         base_price_prorated = max(100, base_price_prorated)  # Minimum 1 ruble
 
+        # Lock user BEFORE discount computation to prevent TOCTOU on promo group
+        from app.database.crud.user import lock_user_for_pricing
+
+        user = await lock_user_for_pricing(db, user.id)
+
         # Apply discount from promo group
         period_hint_days = days_left
         discount_result = _apply_addon_discount(user, 'devices', base_price_prorated, period_hint_days)
@@ -2977,8 +2941,7 @@ async def get_available_countries(
     await db.refresh(user, ['subscription'])
 
     promo_group_id = user.promo_group_id
-    # Exclude trial-only servers from available servers for purchase
-    available_servers = await get_available_server_squads(db, promo_group_id=promo_group_id, exclude_trial_only=True)
+    available_servers = await get_available_server_squads(db, promo_group_id=promo_group_id)
 
     connected_squads = []
     days_left = 0
@@ -2989,11 +2952,10 @@ async def get_available_countries(
             delta = user.subscription.end_date - datetime.now(UTC)
             days_left = max(0, delta.days)
 
-    # Get discount from promo group
-    servers_discount_percent = 0
-    promo_group = user.get_primary_promo_group() if hasattr(user, 'get_primary_promo_group') else None
-    if promo_group:
-        servers_discount_percent = promo_group.get_discount_percent('servers', None)
+    # Get discount from promo group via PricingEngine (respects apply_discounts_to_addons flag)
+    from app.services.pricing_engine import PricingEngine
+
+    servers_discount_percent = PricingEngine.get_addon_discount_percent(user, 'servers', None)
 
     countries = []
     for server in available_servers:
@@ -3076,8 +3038,7 @@ async def update_countries(
     current_countries = user.subscription.connected_squads or []
     promo_group_id = user.promo_group_id
 
-    # Exclude trial-only servers from available servers for purchase
-    available_servers = await get_available_server_squads(db, promo_group_id=promo_group_id, exclude_trial_only=True)
+    available_servers = await get_available_server_squads(db, promo_group_id=promo_group_id)
     allowed_country_ids = {server.squad_uuid for server in available_servers}
 
     # Validate selected countries
@@ -3097,15 +3058,19 @@ async def update_countries(
             'connected_squads': current_countries,
         }
 
+    # Lock user row to prevent TOCTOU on promo-offer state
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     # Calculate cost for added servers
     total_cost = 0
     added_names = []
     removed_names = []
 
-    servers_discount_percent = 0
-    promo_group = user.get_primary_promo_group() if hasattr(user, 'get_primary_promo_group') else None
-    if promo_group:
-        servers_discount_percent = promo_group.get_discount_percent('servers', None)
+    from app.services.pricing_engine import PricingEngine
+
+    servers_discount_percent = PricingEngine.get_addon_discount_percent(user, 'servers', None)
 
     added_server_prices = []
 
@@ -3903,82 +3868,18 @@ async def preview_tariff_switch(
         delta = user.subscription.end_date - datetime.now(UTC)
         remaining_days = max(0, delta.days)
 
-    # Calculate switch cost
-    current_is_daily = getattr(current_tariff, 'is_daily', False) if current_tariff else False
-    new_is_daily = getattr(new_tariff, 'is_daily', False)
-    switching_to_daily = not current_is_daily and new_is_daily
-    switching_from_daily = current_is_daily and not new_is_daily
-
-    def get_monthly_price(tariff) -> int:
-        """Get 30-day price from tariff, or calculate from closest period."""
-        if not tariff or not tariff.period_prices:
-            return 0
-        # Try to get 30-day price directly
-        if '30' in tariff.period_prices:
-            return tariff.period_prices['30']
-        # Find closest period and calculate monthly equivalent
-        min_period = None
-        min_price = 0
-        for period_str, price in tariff.period_prices.items():
-            period_days = int(period_str)
-            if min_period is None or period_days < min_period:
-                min_period = period_days
-                min_price = price
-        if min_period and min_period > 0:
-            return int(min_price * 30 / min_period)
-        return 0
-
-    # Get period discount percent for cost calculation
-    period_discount_percent = _get_period_discount_percent(user, remaining_days if remaining_days > 0 else 30)
-    base_upgrade_cost = 0
-    discount_value = 0
-
-    if switching_to_daily:
-        # Switching TO daily - pay first day price
-        daily_price = getattr(new_tariff, 'daily_price_kopeks', 0)
-        base_upgrade_cost = daily_price
-        # Apply discount to daily price
-        if period_discount_percent > 0 and base_upgrade_cost > 0:
-            discount_value = int(base_upgrade_cost * period_discount_percent / 100)
-            upgrade_cost = base_upgrade_cost - discount_value
-        else:
-            upgrade_cost = base_upgrade_cost
-        is_upgrade = upgrade_cost > 0
-    elif switching_from_daily:
-        # Switching FROM daily TO periodic - full payment for new tariff
-        min_period_price = 0
-        if new_tariff.period_prices:
-            min_period_price = min(new_tariff.period_prices.values())
-        base_upgrade_cost = min_period_price
-        # Apply discount
-        if period_discount_percent > 0 and base_upgrade_cost > 0:
-            discount_value = int(base_upgrade_cost * period_discount_percent / 100)
-            upgrade_cost = base_upgrade_cost - discount_value
-        else:
-            upgrade_cost = base_upgrade_cost
-        is_upgrade = upgrade_cost > 0
-    else:
-        # Calculate proportional cost difference using monthly prices
-        current_monthly = get_monthly_price(current_tariff)
-        new_monthly = get_monthly_price(new_tariff)
-
-        price_diff = new_monthly - current_monthly
-
-        if price_diff > 0:
-            # Upgrade - pay proportional difference
-            base_upgrade_cost = int(price_diff * remaining_days / 30)
-            # Apply discount to upgrade cost
-            if period_discount_percent > 0 and base_upgrade_cost > 0:
-                discount_value = int(base_upgrade_cost * period_discount_percent / 100)
-                upgrade_cost = base_upgrade_cost - discount_value
-            else:
-                upgrade_cost = base_upgrade_cost
-            is_upgrade = True
-        else:
-            # Downgrade or same - free
-            upgrade_cost = 0
-            base_upgrade_cost = 0
-            is_upgrade = False
+    # Calculate switch cost (PricingEngine handles all cases: periodic↔periodic, daily→periodic, periodic→daily)
+    switch_result = pricing_engine.calculate_tariff_switch_cost(
+        current_tariff,
+        new_tariff,
+        remaining_days,
+        user=user,
+    )
+    upgrade_cost = switch_result.upgrade_cost
+    is_upgrade = switch_result.is_upgrade
+    base_upgrade_cost = switch_result.raw_cost
+    discount_value = switch_result.discount_value
+    period_discount_percent = switch_result.effective_discount_pct
 
     balance = user.balance_kopeks or 0
     has_enough = balance >= upgrade_cost
@@ -4090,88 +3991,41 @@ async def switch_tariff(
             detail='Tariff not available',
         )
 
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     # Calculate remaining days
     remaining_days = 0
-    if user.subscription.end_date and user.subscription.end_date > datetime.now(UTC):
-        delta = user.subscription.end_date - datetime.now(UTC)
+    if subscription.end_date and subscription.end_date > datetime.now(UTC):
+        delta = subscription.end_date - datetime.now(UTC)
         remaining_days = max(0, delta.days)
 
-    # Calculate cost
-    current_is_daily = getattr(current_tariff, 'is_daily', False) if current_tariff else False
+    # Calculate cost (PricingEngine handles all cases: periodic↔periodic, daily→periodic, periodic→daily)
+    switch_result = pricing_engine.calculate_tariff_switch_cost(
+        current_tariff,
+        new_tariff,
+        remaining_days,
+        user=user,
+    )
+    upgrade_cost = switch_result.upgrade_cost
+    base_upgrade_cost = switch_result.raw_cost
+    discount_value = switch_result.discount_value
+    period_discount_percent = switch_result.effective_discount_pct
+    new_period_days = switch_result.new_period_days
+
+    # Validate daily price for switching TO daily
     new_is_daily = getattr(new_tariff, 'is_daily', False)
-    switching_from_daily = current_is_daily and not new_is_daily
+    current_is_daily = getattr(current_tariff, 'is_daily', False) if current_tariff else False
     switching_to_daily = not current_is_daily and new_is_daily
+    switching_from_daily = current_is_daily and not new_is_daily
 
-    # Get period discount percent for cost calculation
-    period_discount_percent = _get_period_discount_percent(user, remaining_days if remaining_days > 0 else 30)
-    base_upgrade_cost = 0
-    discount_value = 0
-
-    if switching_to_daily:
-        # Switching TO daily tariff - charge first day price
-        daily_price = getattr(new_tariff, 'daily_price_kopeks', 0)
-        if daily_price <= 0:
-            raise HTTPException(
-                status_code=status.HTTP_400_BAD_REQUEST,
-                detail='Daily tariff has invalid price',
-            )
-        base_upgrade_cost = daily_price
-        # Apply discount
-        if period_discount_percent > 0 and base_upgrade_cost > 0:
-            discount_value = int(base_upgrade_cost * period_discount_percent / 100)
-            upgrade_cost = base_upgrade_cost - discount_value
-        else:
-            upgrade_cost = base_upgrade_cost
-        new_period_days = 1  # Daily tariff starts with 1 day
-    elif switching_from_daily:
-        # Switch FROM daily to regular tariff - pay for minimum period
-        min_period_days = 30
-        min_period_price = 0
-        if new_tariff.period_prices:
-            min_period_days = min(int(k) for k in new_tariff.period_prices.keys())
-            min_period_price = new_tariff.period_prices.get(str(min_period_days), 0)
-        base_upgrade_cost = min_period_price
-        # Apply discount
-        if period_discount_percent > 0 and base_upgrade_cost > 0:
-            discount_value = int(base_upgrade_cost * period_discount_percent / 100)
-            upgrade_cost = base_upgrade_cost - discount_value
-        else:
-            upgrade_cost = base_upgrade_cost
-        new_period_days = min_period_days
-    else:
-        # Regular tariff switch - calculate proportional cost difference using monthly prices
-        def get_monthly_price(tariff) -> int:
-            if not tariff or not tariff.period_prices:
-                return 0
-            if '30' in tariff.period_prices:
-                return tariff.period_prices['30']
-            min_period = None
-            min_price = 0
-            for period_str, price in tariff.period_prices.items():
-                period_days = int(period_str)
-                if min_period is None or period_days < min_period:
-                    min_period = period_days
-                    min_price = price
-            if min_period and min_period > 0:
-                return int(min_price * 30 / min_period)
-            return 0
-
-        current_monthly = get_monthly_price(current_tariff)
-        new_monthly = get_monthly_price(new_tariff)
-        price_diff = new_monthly - current_monthly
-
-        if price_diff > 0:
-            base_upgrade_cost = int(price_diff * remaining_days / 30)
-            # Apply discount
-            if period_discount_percent > 0 and base_upgrade_cost > 0:
-                discount_value = int(base_upgrade_cost * period_discount_percent / 100)
-                upgrade_cost = base_upgrade_cost - discount_value
-            else:
-                upgrade_cost = base_upgrade_cost
-        else:
-            upgrade_cost = 0
-            base_upgrade_cost = 0
-        new_period_days = 0
+    if switching_to_daily and (getattr(new_tariff, 'daily_price_kopeks', 0) or 0) <= 0:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail='Daily tariff has invalid price',
+        )
 
     # Charge if upgrade
     if upgrade_cost > 0:
@@ -4202,6 +4056,7 @@ async def switch_tariff(
             user,
             upgrade_cost,
             description,
+            consume_promo_offer=switch_result.offer_discount_pct > 0,
             mark_as_paid_subscription=True,
             commit=False,
         )
@@ -4359,7 +4214,7 @@ async def switch_tariff(
         'success': True,
         'message': f"Switched from '{old_tariff_name}' to '{new_tariff.name}'"
         + (' (devices reset)' if devices_reset else ''),
-        'subscription': _subscription_to_response(subscription),
+        'subscription': _subscription_to_response(subscription, user=user),
         'old_tariff_name': old_tariff_name,
         'new_tariff_id': new_tariff.id,
         'new_tariff_name': new_tariff.name,
@@ -4426,7 +4281,21 @@ async def toggle_subscription_pause(
         new_paused_state = not is_currently_paused
     user.subscription.is_daily_paused = new_paused_state
 
-    daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+    raw_daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+
+    # Lock user BEFORE discount computation to prevent TOCTOU on promo group
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
+    # Apply group discount to daily price (consistent with DailySubscriptionService and miniapp resume)
+    from app.services.pricing_engine import PricingEngine
+
+    promo_group = PricingEngine.resolve_promo_group(user)
+    daily_group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+    daily_price = (
+        PricingEngine.apply_discount(raw_daily_price, daily_group_pct) if daily_group_pct > 0 else raw_daily_price
+    )
 
     # If resuming, check balance and charge
     if not new_paused_state:
@@ -4568,22 +4437,16 @@ async def switch_traffic_package(
         # Upgrade - charge difference
         price_diff = new_price - current_price
 
-        # Apply promo discount
-        traffic_discount_percent = 0
-        promo_group = (
-            user.get_primary_promo_group()
-            if hasattr(user, 'get_primary_promo_group')
-            else getattr(user, 'promo_group', None)
-        )
-        if promo_group:
-            apply_to_addons = getattr(promo_group, 'apply_discounts_to_addons', True)
-            if apply_to_addons:
-                traffic_discount_percent = max(
-                    0, min(100, int(getattr(promo_group, 'traffic_discount_percent', 0) or 0))
-                )
+        # Lock user row to prevent TOCTOU on promo-offer state
+        from app.database.crud.user import lock_user_for_pricing
 
-        if traffic_discount_percent > 0:
-            price_diff = int(price_diff * (100 - traffic_discount_percent) / 100)
+        user = await lock_user_for_pricing(db, user.id)
+
+        # Apply promo discount via PricingEngine
+        price_diff, _discount_val, traffic_discount_percent = pricing_engine.calculate_traffic_discount(
+            price_diff,
+            user,
+        )
 
         # Prorated calculation
         final_price, days_charged = calculate_prorated_price(price_diff, user.subscription.end_date)

app/database/crud/server_squad.py

@@ -141,8 +141,12 @@ async def get_available_server_squads(
         .order_by(ServerSquad.sort_order, ServerSquad.display_name)
     )
 
-    if exclude_trial_only:
-        query = query.where(ServerSquad.is_trial_eligible.is_(False))
+    # НЕ фильтруем по is_trial_eligible — это поле означает "доступен для триала",
+    # а НЕ "только для триала". Сквад может быть одновременно триальным и платным.
+    # Фильтр exclude_trial_only убирал единственный доступный сквад, из-за чего
+    # пользователи без триала получали пустой connected_squads при покупке.
+    # Параметр exclude_trial_only сохранён для обратной совместимости, но не используется.
+    # TODO: если нужна логика "только для триала", добавить отдельное поле is_trial_only
 
     if promo_group_id is not None:
         query = query.join(ServerSquad.allowed_promo_groups).where(PromoGroup.id == promo_group_id)

app/database/crud/subscription.py

@@ -1,6 +1,5 @@
 from collections.abc import Iterable
 from datetime import UTC, datetime, timedelta
-from typing import Optional
 
 import structlog
 from sqlalchemy import and_, delete, func, select
@@ -11,7 +10,6 @@ from sqlalchemy.orm.exc import StaleDataError
 from app.config import settings
 from app.database.crud.notification import clear_notifications
 from app.database.models import (
-    PromoGroup,
     Subscription,
     SubscriptionServer,
     SubscriptionStatus,
@@ -20,7 +18,6 @@ from app.database.models import (
     User,
     UserStatus,
 )
-from app.utils.pricing_utils import calculate_months_from_days
 from app.utils.timezone import format_local_datetime
 
 
@@ -221,6 +218,23 @@ async def create_paid_subscription(
     if device_limit is None:
         device_limit = settings.DEFAULT_DEVICE_LIMIT
 
+    # Fallback: если connected_squads пустой — берём первый доступный сквад
+    final_squads = list(connected_squads or [])
+    if not final_squads:
+        try:
+            from app.database.crud.server_squad import get_available_server_squads
+
+            available = await get_available_server_squads(db)
+            if available:
+                final_squads = [available[0].squad_uuid]
+                logger.warning(
+                    '⚠️ connected_squads пустой при создании подписки, используем fallback сквад',
+                    user_id=user_id,
+                    fallback_squad=final_squads[0],
+                )
+        except Exception as error:
+            logger.error('❌ Не удалось получить fallback сквад', user_id=user_id, error=error)
+
     subscription = Subscription(
         user_id=user_id,
         status=SubscriptionStatus.ACTIVE.value,
@@ -229,7 +243,7 @@ async def create_paid_subscription(
         end_date=end_date,
         traffic_limit_gb=traffic_limit_gb,
         device_limit=device_limit,
-        connected_squads=connected_squads or [],
+        connected_squads=final_squads,
         autopay_enabled=settings.is_autopay_enabled_by_default(),
         autopay_days_before=settings.DEFAULT_AUTOPAY_DAYS_BEFORE,
         tariff_id=tariff_id,
@@ -249,7 +263,7 @@ async def create_paid_subscription(
         status=subscription.status,
     )
 
-    squad_uuids = list(connected_squads or [])
+    squad_uuids = list(final_squads)
     if update_server_counters and squad_uuids:
         try:
             from app.database.crud.server_squad import (
@@ -299,7 +313,25 @@ async def replace_subscription(
 
     current_time = datetime.now(UTC)
     old_squads = set(subscription.connected_squads or [])
-    new_squads = set(connected_squads or [])
+
+    # Fallback: если connected_squads пустой — берём первый доступный сквад
+    final_connected = list(connected_squads or [])
+    if not final_connected:
+        try:
+            from app.database.crud.server_squad import get_available_server_squads
+
+            available = await get_available_server_squads(db)
+            if available:
+                final_connected = [available[0].squad_uuid]
+                logger.warning(
+                    '⚠️ connected_squads пустой при замене подписки, используем fallback сквад',
+                    subscription_id=subscription.id,
+                    fallback_squad=final_connected[0],
+                )
+        except Exception as error:
+            logger.error('❌ Не удалось получить fallback сквад', subscription_id=subscription.id, error=error)
+
+    new_squads = set(final_connected)
 
     new_autopay_enabled = subscription.autopay_enabled if autopay_enabled is None else autopay_enabled
     new_autopay_days_before = subscription.autopay_days_before if autopay_days_before is None else autopay_days_before
@@ -549,9 +581,17 @@ async def extend_subscription(
         logger.info('📱 Обновлен лимит устройств: →', old_devices=old_devices, device_limit=device_limit)
 
     if connected_squads is not None:
-        old_squads = subscription.connected_squads
-        subscription.connected_squads = connected_squads
-        logger.info('🌍 Обновлены сквады: →', old_squads=old_squads, connected_squads=connected_squads)
+        # Не перезаписываем существующие сквады пустым списком
+        if connected_squads or not subscription.connected_squads:
+            old_squads = subscription.connected_squads
+            subscription.connected_squads = connected_squads
+            logger.info('🌍 Обновлены сквады: →', old_squads=old_squads, connected_squads=connected_squads)
+        else:
+            logger.warning(
+                '⚠️ Попытка перезаписать сквады пустым списком, сохраняем текущие',
+                subscription_id=subscription.id,
+                current_squads=subscription.connected_squads,
+            )
 
     # Обработка daily полей при смене тарифа
     if is_tariff_change and tariff_id is not None:
@@ -1198,212 +1238,6 @@ async def add_subscription_servers(
     return subscription
 
 
-async def get_server_monthly_price(db: AsyncSession, server_squad_id: int) -> int:
-    from app.database.models import ServerSquad
-
-    result = await db.execute(select(ServerSquad.price_kopeks).where(ServerSquad.id == server_squad_id))
-    return result.scalar() or 0
-
-
-async def get_servers_monthly_prices(
-    db: AsyncSession,
-    server_squad_ids: list[int],
-    *,
-    user: Optional['User'] = None,
-) -> list[int]:
-    """Получает месячные цены серверов с проверкой доступности для промогруппы пользователя."""
-    from sqlalchemy.orm import selectinload
-
-    from app.database.models import ServerSquad
-
-    prices = []
-
-    # Загружаем промогруппы пользователя если нужно
-    user_promo_group = None
-    user_promo_group_id = None
-    if user:
-        try:
-            # Пробуем загрузить промогруппы если ещё не загружены
-            await db.refresh(user, ['user_promo_groups', 'promo_group'])
-        except Exception:
-            pass
-        try:
-            user_promo_group = user.get_primary_promo_group()
-            user_promo_group_id = user_promo_group.id if user_promo_group else None
-        except Exception as e:
-            logger.warning('Не удалось получить промогруппу пользователя', error=e)
-
-    for server_id in server_squad_ids:
-        # Загружаем сервер с промогруппами
-        result = await db.execute(
-            select(ServerSquad)
-            .options(selectinload(ServerSquad.allowed_promo_groups))
-            .where(ServerSquad.id == server_id)
-        )
-        server = result.scalar_one_or_none()
-
-        if not server:
-            prices.append(0)
-            continue
-
-        # Проверяем доступность сервера для промогруппы пользователя
-        is_allowed = True
-        if user_promo_group_id is not None and server.allowed_promo_groups:
-            allowed_ids = {pg.id for pg in server.allowed_promo_groups}
-            is_allowed = user_promo_group_id in allowed_ids
-
-        if server.is_available and is_allowed:
-            prices.append(server.price_kopeks)
-        else:
-            # Сервер недоступен для промогруппы пользователя
-            logger.warning(
-                '⚠️ Сервер (id=) недоступен для промогруппы пользователя (promo_group_id=), allowed_promo_groups',
-                display_name=server.display_name,
-                server_id=server_id,
-                user_promo_group_id=user_promo_group_id,
-                value=[pg.id for pg in server.allowed_promo_groups] if server.allowed_promo_groups else [],
-            )
-            prices.append(server.price_kopeks)  # Всё равно берём реальную цену
-
-    return prices
-
-
-def _get_discount_percent(
-    user: User | None,
-    promo_group: PromoGroup | None,
-    category: str,
-    *,
-    period_days: int | None = None,
-) -> int:
-    if user is not None:
-        try:
-            return user.get_promo_discount(category, period_days)
-        except AttributeError:
-            pass
-
-    if promo_group is not None:
-        return promo_group.get_discount_percent(category, period_days)
-
-    return 0
-
-
-async def calculate_subscription_total_cost(
-    db: AsyncSession,
-    period_days: int,
-    traffic_gb: int,
-    server_squad_ids: list[int],
-    devices: int,
-    *,
-    user: User | None = None,
-    promo_group: PromoGroup | None = None,
-) -> tuple[int, dict]:
-    from app.config import PERIOD_PRICES
-
-    months_in_period = calculate_months_from_days(period_days)
-
-    base_price_original = PERIOD_PRICES.get(period_days, 0)
-    period_discount_percent = _get_discount_percent(
-        user,
-        promo_group,
-        'period',
-        period_days=period_days,
-    )
-    base_discount_total = base_price_original * period_discount_percent // 100
-    base_price = base_price_original - base_discount_total
-
-    promo_group = promo_group or (user.promo_group if user else None)
-
-    traffic_price_per_month = settings.get_traffic_price(traffic_gb)
-    traffic_discount_percent = _get_discount_percent(
-        user,
-        promo_group,
-        'traffic',
-        period_days=period_days,
-    )
-    traffic_discount_per_month = traffic_price_per_month * traffic_discount_percent // 100
-    discounted_traffic_per_month = traffic_price_per_month - traffic_discount_per_month
-    total_traffic_price = discounted_traffic_per_month * months_in_period
-    total_traffic_discount = traffic_discount_per_month * months_in_period
-
-    servers_prices = await get_servers_monthly_prices(db, server_squad_ids, user=user)
-    servers_price_per_month = sum(servers_prices)
-    servers_discount_percent = _get_discount_percent(
-        user,
-        promo_group,
-        'servers',
-        period_days=period_days,
-    )
-    servers_discount_per_month = servers_price_per_month * servers_discount_percent // 100
-    discounted_servers_per_month = servers_price_per_month - servers_discount_per_month
-    total_servers_price = discounted_servers_per_month * months_in_period
-    total_servers_discount = servers_discount_per_month * months_in_period
-
-    additional_devices = max(0, devices - settings.DEFAULT_DEVICE_LIMIT)
-    devices_price_per_month = additional_devices * settings.PRICE_PER_DEVICE
-    devices_discount_percent = _get_discount_percent(
-        user,
-        promo_group,
-        'devices',
-        period_days=period_days,
-    )
-    devices_discount_per_month = devices_price_per_month * devices_discount_percent // 100
-    discounted_devices_per_month = devices_price_per_month - devices_discount_per_month
-    total_devices_price = discounted_devices_per_month * months_in_period
-    total_devices_discount = devices_discount_per_month * months_in_period
-
-    total_cost = base_price + total_traffic_price + total_servers_price + total_devices_price
-
-    details = {
-        'base_price': base_price,
-        'base_price_original': base_price_original,
-        'base_discount_percent': period_discount_percent,
-        'base_discount_total': base_discount_total,
-        'traffic_price_per_month': traffic_price_per_month,
-        'traffic_discount_percent': traffic_discount_percent,
-        'traffic_discount_total': total_traffic_discount,
-        'total_traffic_price': total_traffic_price,
-        'servers_price_per_month': servers_price_per_month,
-        'servers_discount_percent': servers_discount_percent,
-        'servers_discount_total': total_servers_discount,
-        'total_servers_price': total_servers_price,
-        'devices_price_per_month': devices_price_per_month,
-        'devices_discount_percent': devices_discount_percent,
-        'devices_discount_total': total_devices_discount,
-        'total_devices_price': total_devices_price,
-        'months_in_period': months_in_period,
-        'servers_individual_prices': [
-            (price - (price * servers_discount_percent // 100)) * months_in_period for price in servers_prices
-        ],
-    }
-
-    logger.debug(
-        '📊 Расчет стоимости подписки на дней ( мес)', period_days=period_days, months_in_period=months_in_period
-    )
-    logger.debug('Базовый период: ₽', base_price=base_price / 100)
-    if total_traffic_price > 0:
-        message = f'   Трафик: {traffic_price_per_month / 100}₽/мес × {months_in_period} = {total_traffic_price / 100}₽'
-        if total_traffic_discount > 0:
-            message += f' (скидка {traffic_discount_percent}%: -{total_traffic_discount / 100}₽)'
-        logger.debug(message)
-    if total_servers_price > 0:
-        message = (
-            f'   Серверы: {servers_price_per_month / 100}₽/мес × {months_in_period} = {total_servers_price / 100}₽'
-        )
-        if total_servers_discount > 0:
-            message += f' (скидка {servers_discount_percent}%: -{total_servers_discount / 100}₽)'
-        logger.debug(message)
-    if total_devices_price > 0:
-        message = (
-            f'   Устройства: {devices_price_per_month / 100}₽/мес × {months_in_period} = {total_devices_price / 100}₽'
-        )
-        if total_devices_discount > 0:
-            message += f' (скидка {devices_discount_percent}%: -{total_devices_discount / 100}₽)'
-        logger.debug(message)
-    logger.debug('ИТОГО: ₽', total_cost=total_cost / 100)
-
-    return total_cost, details
-
-
 async def get_subscription_server_ids(db: AsyncSession, subscription_id: int) -> list[int]:
     result = await db.execute(
         select(SubscriptionServer.server_squad_id).where(SubscriptionServer.subscription_id == subscription_id)
@@ -1901,8 +1735,9 @@ async def get_disabled_daily_subscriptions_for_resume(
                 # Не возобновляем подписки, приостановленные пользователем вручную
                 # is_(False) не ловит NULL, поэтому добавляем OR is_(None)
                 (Subscription.is_daily_paused.is_(False) | Subscription.is_daily_paused.is_(None)),
-                # Баланс пользователя >= суточной цены тарифа
-                User.balance_kopeks >= Tariff.daily_price_kopeks,
+                # Баланс пользователя > 0 (permissive pre-filter;
+                # actual discounted price check happens in _process_single_charge)
+                User.balance_kopeks > 0,
             )
         )
     )
@@ -1947,8 +1782,9 @@ async def get_expired_daily_subscriptions_for_recovery(db: AsyncSession) -> list
                 Subscription.is_trial.is_(False),
                 # Только недавно экспайренные
                 Subscription.updated_at >= recovery_threshold,
-                # Баланс достаточен для списания
-                User.balance_kopeks >= Tariff.daily_price_kopeks,
+                # Баланс > 0 (permissive pre-filter;
+                # actual discounted price check happens in _process_single_charge)
+                User.balance_kopeks > 0,
             )
         )
     )

app/database/crud/user.py

@@ -528,6 +528,26 @@ async def add_user_balance_by_id(
         return False
 
 
+async def lock_user_for_pricing(db: AsyncSession, user_id: int) -> User:
+    """Lock user row with FOR UPDATE and return refreshed instance.
+
+    Call BEFORE computing prices that depend on promo offer state
+    to prevent TOCTOU race conditions where two concurrent requests
+    both read the same promo offer discount and charge a discounted price.
+    """
+    result = await db.execute(
+        select(User)
+        .where(User.id == user_id)
+        .options(
+            selectinload(User.user_promo_groups).selectinload(UserPromoGroup.promo_group),
+            selectinload(User.promo_group),
+        )
+        .with_for_update()
+        .execution_options(populate_existing=True)
+    )
+    return result.scalar_one()
+
+
 async def subtract_user_balance(
     db: AsyncSession,
     user: User,

app/handlers/admin/messages.py

@@ -1103,13 +1103,27 @@ async def confirm_button_selection(callback: types.CallbackQuery, db_user: User,
                 await callback.message.delete()
             except Exception:
                 pass
-            await callback.bot.send_photo(
-                chat_id=callback.message.chat.id,
-                photo=media_file_id,
-                caption=preview_text,
-                reply_markup=types.InlineKeyboardMarkup(inline_keyboard=keyboard),
-                parse_mode='HTML',
-            )
+            # Telegram ограничивает caption до 1024 символов
+            if len(preview_text) <= 1024:
+                await callback.bot.send_photo(
+                    chat_id=callback.message.chat.id,
+                    photo=media_file_id,
+                    caption=preview_text,
+                    reply_markup=types.InlineKeyboardMarkup(inline_keyboard=keyboard),
+                    parse_mode='HTML',
+                )
+            else:
+                # Фото без caption + текст отдельным сообщением
+                await callback.bot.send_photo(
+                    chat_id=callback.message.chat.id,
+                    photo=media_file_id,
+                )
+                await callback.bot.send_message(
+                    chat_id=callback.message.chat.id,
+                    text=preview_text,
+                    reply_markup=types.InlineKeyboardMarkup(inline_keyboard=keyboard),
+                    parse_mode='HTML',
+                )
         else:
             # Если нет file_id, используем safe редактирование
             await safe_edit_or_send_text(
@@ -1244,13 +1258,27 @@ async def confirm_broadcast(callback: types.CallbackQuery, db_user: User, state:
                             'video': 'video',
                             'document': 'document',
                         }[media_type]
-                        await send_method(
-                            chat_id=telegram_id,
-                            **{media_kwarg: media_file_id},
-                            caption=message_text,
-                            parse_mode='HTML',
-                            reply_markup=broadcast_keyboard,
-                        )
+                        # Telegram ограничивает caption до 1024 символов
+                        if len(message_text) <= 1024:
+                            await send_method(
+                                chat_id=telegram_id,
+                                **{media_kwarg: media_file_id},
+                                caption=message_text,
+                                parse_mode='HTML',
+                                reply_markup=broadcast_keyboard,
+                            )
+                        else:
+                            # Медиа без caption + текст отдельным сообщением
+                            await send_method(
+                                chat_id=telegram_id,
+                                **{media_kwarg: media_file_id},
+                            )
+                            await callback.bot.send_message(
+                                chat_id=telegram_id,
+                                text=message_text,
+                                parse_mode='HTML',
+                                reply_markup=broadcast_keyboard,
+                            )
                     else:
                         # Неизвестный media_type — отправляем как текст
                         await callback.bot.send_message(

app/handlers/admin/users.py

@@ -4457,6 +4457,11 @@ async def admin_buy_subscription_execute(callback: types.CallbackQuery, db_user:
 
     subscription_service = SubscriptionService()
 
+    # TOCTOU protection: lock user row before pricing to prevent concurrent balance modifications
+    from app.database.crud.user import lock_user_for_pricing
+
+    target_user = await lock_user_for_pricing(db, target_user.id)
+
     try:
         price_kopeks = await _calculate_subscription_period_price(
             db,
@@ -4914,7 +4919,7 @@ async def admin_buy_tariff_execute(callback: types.CallbackQuery, db_user: User,
     user_id = int(parts[4])
     tariff_id = int(parts[5])
     period = int(parts[6])
-    price_kopeks = int(parts[7])
+    price_kopeks_from_callback = int(parts[7])
 
     user_service = UserService()
     profile = await user_service.get_user_profile(db, user_id)
@@ -4933,7 +4938,48 @@ async def admin_buy_tariff_execute(callback: types.CallbackQuery, db_user: User,
         await callback.answer('❌ Тариф недоступен', show_alert=True)
         return
 
-    # Проверяем баланс ещё раз
+    # TOCTOU protection: lock user row before pricing to prevent concurrent balance modifications
+    from app.database.crud.user import lock_user_for_pricing
+
+    target_user = await lock_user_for_pricing(db, target_user.id)
+
+    from app.database.crud.subscription import get_subscription_by_user_id
+
+    existing_subscription = await get_subscription_by_user_id(db, target_user.id)
+
+    # Recalculate price from locked state (callback data may be stale)
+    from app.services.pricing_engine import PricingEngine
+
+    pricing_engine = PricingEngine()
+    device_limit = None
+    if existing_subscription and existing_subscription.tariff_id == tariff_id:
+        device_limit = existing_subscription.device_limit
+
+    try:
+        result = await pricing_engine.calculate_tariff_purchase_price(
+            tariff,
+            period,
+            device_limit=device_limit,
+            user=target_user,
+        )
+        price_kopeks = result.final_total
+    except Exception as e:
+        logger.error(
+            'Ошибка расчёта стоимости тарифа при списании средств админом для пользователя',
+            telegram_id=target_user.telegram_id,
+            e=e,
+        )
+        await callback.answer('❌ Не удалось рассчитать стоимость тарифа', show_alert=True)
+        return
+
+    if price_kopeks_from_callback != price_kopeks:
+        logger.info(
+            'Стоимость тарифа для пользователя изменилась перед списанием',
+            telegram_id=target_user.telegram_id,
+            price_kopeks_from_callback=price_kopeks_from_callback,
+            price_kopeks=price_kopeks,
+        )
+
     if target_user.balance_kopeks < price_kopeks:
         await callback.answer('❌ Недостаточно средств на балансе', show_alert=True)
         return
@@ -4942,7 +4988,6 @@ async def admin_buy_tariff_execute(callback: types.CallbackQuery, db_user: User,
         from app.database.crud.subscription import (
             create_paid_subscription,
             extend_subscription,
-            get_subscription_by_user_id,
         )
         from app.database.crud.transaction import create_transaction
         from app.database.crud.user import subtract_user_balance

app/handlers/balance/main.py

@@ -18,7 +18,6 @@ from app.keyboards.inline import (
 from app.localization.texts import get_texts
 from app.states import BalanceStates
 from app.utils.decorators import error_handler
-from app.utils.price_display import calculate_user_price
 
 
 logger = structlog.get_logger(__name__)
@@ -153,7 +152,8 @@ async def get_quick_amount_buttons(language: str, user: User) -> list:
     """
     Generate quick amount buttons with user-specific pricing and discounts.
 
-    Includes full subscription cost: base period price + devices + servers + traffic.
+    Uses PricingEngine as the single source of truth for all price calculations,
+    including base period price, devices, servers, traffic, and per-category discounts.
 
     Args:
         language: User's language for formatting
@@ -165,135 +165,77 @@ async def get_quick_amount_buttons(language: str, user: User) -> list:
     if not settings.is_quick_amount_buttons_enabled():
         return []
 
-    from app.config import PERIOD_PRICES
     from app.database.crud.subscription import get_subscription_by_user_id
     from app.database.database import AsyncSessionLocal
-    from app.utils.pricing_utils import apply_percentage_discount, calculate_months_from_days
+    from app.services.pricing_engine import pricing_engine
 
     texts = get_texts(language)
 
-    tariff = None
-    tariff_prices = None
-    tariff_periods = None
-    devices_price_per_month = 0
-    servers_per_month_prices: list[int] = []
-    traffic_price_per_month = 0
+    buttons = []
 
     async with AsyncSessionLocal() as db:
         subscription = await get_subscription_by_user_id(db, user.id)
 
-        # В режиме тарифов получаем цены из тарифа пользователя
+        tariff = None
+        tariff_periods = None
         if settings.is_tariffs_mode() and subscription and subscription.tariff_id:
-            from app.database.crud.tariff import get_tariff_by_id
-
-            tariff = await get_tariff_by_id(db, subscription.tariff_id)
+            tariff = subscription.tariff
             if tariff and tariff.period_prices:
-                tariff_prices = {int(k): v for k, v in tariff.period_prices.items()}
-                tariff_periods = sorted(tariff_prices.keys())
+                tariff_periods = sorted(int(k) for k in tariff.period_prices.keys())
 
-        # Получаем стоимость устройств, серверов и трафика из подписки
-        if subscription and not subscription.is_trial:
-            # Устройства: в режиме тарифов используем цену и базовый лимит из тарифа
-            if settings.is_tariffs_mode() and tariff and tariff_prices:
-                tariff_device_price = getattr(tariff, 'device_price_kopeks', None)
-                if tariff_device_price and tariff_device_price > 0:
-                    device_unit_price = tariff_device_price
-                    base_device_limit = tariff.device_limit or 0
-                else:
-                    device_unit_price = settings.PRICE_PER_DEVICE
-                    base_device_limit = settings.DEFAULT_DEVICE_LIMIT
-            else:
-                device_unit_price = settings.PRICE_PER_DEVICE
-                base_device_limit = settings.DEFAULT_DEVICE_LIMIT
-
-            device_limit = subscription.device_limit or base_device_limit
-            additional_devices = max(0, device_limit - base_device_limit)
-            if additional_devices > 0:
-                devices_price_per_month = additional_devices * device_unit_price
-
-            # Серверы
-            connected_squads = subscription.connected_squads or []
-            if connected_squads:
-                from app.services.subscription_service import SubscriptionService
-
-                subscription_service = SubscriptionService()
-                _, servers_per_month_prices = await subscription_service.get_countries_price_by_uuids(
-                    connected_squads, db, promo_group_id=user.promo_group_id
-                )
-
-            # Трафик
-            traffic_price_per_month = settings.get_traffic_price(subscription.traffic_limit_gb)
-
-    buttons = []
-
-    # Используем периоды тарифа в режиме тарифов, иначе стандартные
-    if tariff_periods:
-        periods = tariff_periods[:6]
-    else:
-        periods = settings.get_available_subscription_periods()[:6]
-
-    for period in periods:
-        # Получаем цену из тарифа или из PERIOD_PRICES
-        if tariff_prices and period in tariff_prices:
-            base_price_kopeks = tariff_prices[period]
+        if tariff_periods:
+            periods = tariff_periods[:6]
         else:
-            base_price_kopeks = PERIOD_PRICES.get(period, 0)
+            periods = settings.get_available_subscription_periods()[:6]
 
-        if base_price_kopeks > 0:
-            # Базовая цена периода с промо-скидками
-            price_info = calculate_user_price(user, base_price_kopeks, period, 'period')
-
-            months = calculate_months_from_days(period)
-
-            # Стоимость устройств со скидкой
-            devices_addon = 0
-            if devices_price_per_month > 0:
-                devices_discount = user.get_promo_discount('devices', period)
-                devices_discounted, _ = apply_percentage_discount(devices_price_per_month, devices_discount)
-                devices_addon = devices_discounted * months
-
-            # Стоимость серверов со скидкой
-            servers_addon = 0
-            if servers_per_month_prices:
-                servers_discount = user.get_promo_discount('servers', period)
-                for server_price in servers_per_month_prices:
-                    discounted, _ = apply_percentage_discount(server_price, servers_discount)
-                    servers_addon += discounted
-                servers_addon *= months
-
-            # Стоимость трафика со скидкой
-            traffic_addon = 0
-            if traffic_price_per_month > 0:
-                traffic_discount = user.get_promo_discount('traffic', period)
-                traffic_discounted, _ = apply_percentage_discount(traffic_price_per_month, traffic_discount)
-                traffic_addon = traffic_discounted * months
-
-            total_price = price_info.final_price + devices_addon + servers_addon + traffic_addon
-            callback_data = f'quick_amount_{total_price}'
-
-            period_label = f'{period} дней'
-
-            # Скидка считается от полной базовой стоимости (период + аддоны без скидок)
-            total_base = (
-                base_price_kopeks
-                + (devices_price_per_month + sum(servers_per_month_prices) + traffic_price_per_month) * months
-            )
-            has_discount = total_base > total_price and total_base > 0
-
-            if has_discount:
-                discount_pct = round((total_base - total_price) * 100 / total_base)
-                if discount_pct > 0:
-                    button_text = (
-                        f'{texts.format_price(total_base)} ➜ '
-                        f'{texts.format_price(total_price)} '
-                        f'(-{discount_pct}%) • {period_label}'
+        for period in periods:
+            try:
+                if tariff and tariff_periods and period in tariff_periods:
+                    result = await pricing_engine.calculate_tariff_purchase_price(
+                        tariff,
+                        period,
+                        device_limit=subscription.device_limit if subscription else None,
+                        user=user,
                     )
+                elif subscription:
+                    result = await pricing_engine.calculate_renewal_price(db, subscription, period, user=user)
+                else:
+                    result = await pricing_engine.calculate_classic_new_subscription_price(
+                        db,
+                        period,
+                        [],
+                        0,
+                        settings.DEFAULT_DEVICE_LIMIT,
+                        user=user,
+                    )
+
+                total_price = result.final_total
+                original_total = result.original_total
+
+                if total_price <= 0:
+                    continue
+
+                callback_data = f'quick_amount_{total_price}'
+                period_label = f'{period} дней'
+
+                has_discount = original_total > total_price and original_total > 0
+                if has_discount:
+                    discount_pct = round((original_total - total_price) * 100 / original_total)
+                    if discount_pct > 0:
+                        button_text = (
+                            f'{texts.format_price(original_total)} ➜ '
+                            f'{texts.format_price(total_price)} '
+                            f'(-{discount_pct}%) • {period_label}'
+                        )
+                    else:
+                        button_text = f'{texts.format_price(total_price)} • {period_label}'
                 else:
                     button_text = f'{texts.format_price(total_price)} • {period_label}'
-            else:
-                button_text = f'{texts.format_price(total_price)} • {period_label}'
 
-            buttons.append(types.InlineKeyboardButton(text=button_text, callback_data=callback_data))
+                buttons.append(types.InlineKeyboardButton(text=button_text, callback_data=callback_data))
+            except Exception:
+                logger.warning('Failed to calculate price for period', period=period)
+                continue
 
     keyboard_rows = []
     for i in range(0, len(buttons), 2):

app/handlers/menu.py

@@ -1249,7 +1249,7 @@ async def handle_activate_button(callback: types.CallbackQuery, db_user: User, d
     """
     texts = get_texts(db_user.language)
 
-    from app.database.crud.server_squad import get_available_server_squads, get_server_ids_by_uuids
+    from app.database.crud.server_squad import get_available_server_squads
     from app.database.crud.subscription import create_paid_subscription, get_subscription_by_user_id
     from app.database.crud.transaction import create_transaction
     from app.database.crud.user import subtract_user_balance
@@ -1287,7 +1287,9 @@ async def handle_activate_button(callback: types.CallbackQuery, db_user: User, d
         if not connected_squads and available_servers:
             connected_squads = [available_servers[0].squad_uuid]
 
-    server_ids = await get_server_ids_by_uuids(db, connected_squads) if connected_squads else []
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
 
     balance = db_user.balance_kopeks
     available_periods = sorted(settings.get_available_subscription_periods(), reverse=True)
@@ -1299,7 +1301,7 @@ async def handle_activate_button(callback: types.CallbackQuery, db_user: User, d
     best_price = 0
     best_pricing = None  # Cache pricing result for reuse in finalize()
 
-    # Для продления используем PricingEngine (единый расчёт для всех поверхностей).
+    # PricingEngine — единый расчёт для всех поверхностей (и продление, и новая подписка).
     from app.services.pricing_engine import pricing_engine
 
     renewal_service = SubscriptionRenewalService() if subscription else None
@@ -1310,9 +1312,15 @@ async def handle_activate_button(callback: types.CallbackQuery, db_user: User, d
                 pricing_result = await pricing_engine.calculate_renewal_price(db, subscription, period, user=db_user)
                 price = pricing_result.final_total
             else:
-                price, _ = await subscription_service.calculate_subscription_price_with_months(
-                    period, traffic_limit_gb, server_ids, device_limit, db, user=db_user
+                new_pricing = await pricing_engine.calculate_classic_new_subscription_price(
+                    db,
+                    period,
+                    connected_squads,
+                    traffic_limit_gb,
+                    device_limit,
+                    user=db_user,
                 )
+                price = new_pricing.final_total
             if price <= balance:
                 best_period = period
                 best_price = price
@@ -1326,9 +1334,15 @@ async def handle_activate_button(callback: types.CallbackQuery, db_user: User, d
                 min_pricing = await pricing_engine.calculate_renewal_price(db, subscription, min_period, user=db_user)
                 min_price = min_pricing.final_total
             else:
-                min_price, _ = await subscription_service.calculate_subscription_price_with_months(
-                    min_period, traffic_limit_gb, server_ids, device_limit, db, user=db_user
+                min_new_pricing = await pricing_engine.calculate_classic_new_subscription_price(
+                    db,
+                    min_period,
+                    connected_squads,
+                    traffic_limit_gb,
+                    device_limit,
+                    user=db_user,
                 )
+                min_price = min_new_pricing.final_total
             missing = min_price - balance
             await callback.answer(
                 texts.t('INSUFFICIENT_FUNDS_DETAILED', f'❌ Недостаточно средств. Не хватает {missing // 100} ₽'),
@@ -1365,12 +1379,14 @@ async def handle_activate_button(callback: types.CallbackQuery, db_user: User, d
             )
         else:
             # Списать баланс ДО создания подписки (чтобы не было orphaned subscription при неудаче)
+            consume_promo = get_user_active_promo_discount_percent(db_user) > 0
             success = await subtract_user_balance(
                 db,
                 db_user,
                 best_price,
                 f'Активация подписки на {best_period} дней',
                 mark_as_paid_subscription=True,
+                consume_promo_offer=consume_promo,
             )
             if not success:
                 await callback.answer('❌ Недостаточно средств', show_alert=True)

app/handlers/simple_subscription.py

@@ -401,13 +401,25 @@ async def handle_simple_subscription_pay_with_balance(
         state_data=data,
     )
 
-    # Рассчитываем цену подписки
+    # Lock user BEFORE pricing to prevent TOCTOU
+    from app.database.crud.user import lock_user_for_pricing, subtract_user_balance
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # Рассчитываем цену подписки (group discounts per-category)
     price_kopeks, price_breakdown = await _calculate_simple_subscription_price(
         db,
         subscription_params,
         user=db_user,
         resolved_squad_uuid=resolved_squad_uuid,
     )
+
+    # PricingEngine already applies promo-offer discount inside calculate_classic_new_subscription_price.
+    # Only determine whether to consume the offer (zero it out after use).
+    from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+    consume_promo = get_user_active_promo_discount_percent(db_user) > 0
+
     total_required = price_kopeks
     logger.warning(
         'SIMPLE_SUBSCRIPTION_DEBUG_PAY_BALANCE | user= | period= | base= | traffic= | devices= | servers= | discount= | total_required= | balance',
@@ -431,15 +443,13 @@ async def handle_simple_subscription_pay_with_balance(
 
     try:
         # Списываем средства с баланса пользователя
-        from app.database.crud.user import subtract_user_balance
-
         purchase_description = f'Оплата подписки на {subscription_params["period_days"]} дней'
         success = await subtract_user_balance(
             db,
             db_user,
             price_kopeks,
             purchase_description,
-            consume_promo_offer=False,
+            consume_promo_offer=consume_promo,
             mark_as_paid_subscription=True,
         )
 
@@ -840,7 +850,7 @@ async def handle_simple_subscription_payment_method(
             state_data=data,
         )
 
-        # Рассчитываем цену подписки
+        # Рассчитываем цену подписки (group discounts per-category)
         price_kopeks, _ = await _calculate_simple_subscription_price(
             db,
             subscription_params,
@@ -848,6 +858,14 @@ async def handle_simple_subscription_payment_method(
             resolved_squad_uuid=resolved_squad_uuid,
         )
 
+        # Apply promo-offer discount on top of group discounts (consistent with balance-pay path)
+        from app.services.pricing_engine import PricingEngine
+        from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+        offer_pct = get_user_active_promo_discount_percent(db_user)
+        if offer_pct > 0:
+            price_kopeks = PricingEngine.apply_discount(price_kopeks, offer_pct)
+
         if payment_method == 'stars':
             # Оплата через Telegram Stars
             order = await purchase_service.create_subscription_order(
@@ -2121,13 +2139,25 @@ async def confirm_simple_subscription_purchase(
         state_data=data,
     )
 
-    # Рассчитываем цену подписки
+    # Lock user BEFORE pricing to prevent TOCTOU
+    from app.database.crud.user import lock_user_for_pricing, subtract_user_balance
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # Рассчитываем цену подписки (group discounts per-category)
     price_kopeks, price_breakdown = await _calculate_simple_subscription_price(
         db,
         subscription_params,
         user=db_user,
         resolved_squad_uuid=resolved_squad_uuid,
     )
+
+    # PricingEngine already applies promo-offer discount inside calculate_classic_new_subscription_price.
+    # Only determine whether to consume the offer (zero it out after use).
+    from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+    consume_promo = get_user_active_promo_discount_percent(db_user) > 0
+
     total_required = price_kopeks
     logger.warning(
         'SIMPLE_SUBSCRIPTION_DEBUG_CONFIRM | user= | period= | base= | traffic= | devices= | servers= | discount= | total_required= | balance',
@@ -2151,15 +2181,13 @@ async def confirm_simple_subscription_purchase(
 
     try:
         # Списываем средства с баланса пользователя
-        from app.database.crud.user import subtract_user_balance
-
         purchase_description = f'Оплата подписки на {subscription_params["period_days"]} дней'
         success = await subtract_user_balance(
             db,
             db_user,
             price_kopeks,
             purchase_description,
-            consume_promo_offer=False,
+            consume_promo_offer=consume_promo,
             mark_as_paid_subscription=True,
         )
 

app/handlers/subscription/common.py

@@ -56,43 +56,6 @@ def _format_text_with_placeholders(template: str, values: dict[str, Any]) -> str
         return template
 
 
-def _get_addon_discount_percent_for_user(
-    user: User | None,
-    category: str,
-    period_days_hint: int | None = None,
-) -> int:
-    if user is None:
-        return 0
-
-    promo_group = user.get_primary_promo_group()
-    if promo_group is None:
-        return 0
-
-    if not getattr(promo_group, 'apply_discounts_to_addons', True):
-        return 0
-
-    try:
-        return user.get_promo_discount(category, period_days_hint)
-    except AttributeError:
-        return 0
-
-
-def _apply_addon_discount(
-    user: User | None,
-    category: str,
-    amount: int,
-    period_days_hint: int | None = None,
-) -> dict[str, int]:
-    percent = _get_addon_discount_percent_for_user(user, category, period_days_hint)
-    discounted_amount, discount_value = apply_percentage_discount(amount, percent)
-
-    return {
-        'discounted': discounted_amount,
-        'discount': discount_value,
-        'percent': percent,
-    }
-
-
 def _get_promo_offer_discount_percent(user: User | None) -> int:
     return get_user_active_promo_discount_percent(user)
 

app/handlers/subscription/countries.py

@@ -5,9 +5,9 @@ from aiogram import types
 from aiogram.fsm.context import FSMContext
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.config import PERIOD_PRICES, settings
+from app.config import settings
 from app.database.crud.transaction import create_transaction
-from app.database.crud.user import subtract_user_balance
+from app.database.crud.user import lock_user_for_pricing, subtract_user_balance
 from app.database.models import TransactionType, User
 from app.keyboards.inline import (
     get_back_keyboard,
@@ -17,6 +17,7 @@ from app.keyboards.inline import (
     get_manage_countries_keyboard,
 )
 from app.localization.texts import get_texts
+from app.services.pricing_engine import PricingEngine, pricing_engine
 from app.services.subscription_checkout_service import (
     save_subscription_checkout_draft,
     should_offer_checkout_resume,
@@ -28,7 +29,7 @@ from app.utils.pricing_utils import (
     calculate_prorated_price,
 )
 
-from .common import _get_addon_discount_percent_for_user, _get_period_hint_from_subscription, logger
+from .common import _get_period_hint_from_subscription, logger
 from .summary import present_subscription_summary
 
 
@@ -58,7 +59,7 @@ async def handle_add_countries(callback: types.CallbackQuery, db_user: User, db:
     current_countries = subscription.connected_squads
 
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    servers_discount_percent = _get_addon_discount_percent_for_user(
+    servers_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'servers',
         period_hint_days,
@@ -194,7 +195,7 @@ async def handle_manage_country(callback: types.CallbackQuery, db_user: User, db
     await state.update_data(countries=current_selected)
 
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    servers_discount_percent = _get_addon_discount_percent_for_user(
+    servers_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'servers',
         period_hint_days,
@@ -257,7 +258,12 @@ async def apply_countries_changes(callback: types.CallbackQuery, db_user: User,
     days_to_pay = max(1, (subscription.end_date - now).days)
 
     period_hint_days = days_to_pay if days_to_pay > 0 else None
-    servers_discount_percent = _get_addon_discount_percent_for_user(
+
+    # TOCTOU protection: lock user row before reading discount and charging balance
+    db_user = await lock_user_for_pricing(db, db_user.id)
+    subscription = db_user.subscription
+
+    servers_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'servers',
         period_hint_days,
@@ -496,31 +502,18 @@ async def select_country(callback: types.CallbackQuery, state: FSMContext, db_us
         await callback.answer('❌ Сервер недоступен для вашей промогруппы', show_alert=True)
         return
 
-    period_base_price = PERIOD_PRICES.get(data['period_days'], 0)
-    discounted_base_price, _ = apply_percentage_discount(
-        period_base_price,
-        db_user.get_promo_discount('period', data['period_days']),
-    )
-
-    base_price = discounted_base_price + settings.get_traffic_price(data['traffic_gb'])
-
-    try:
-        subscription_service = SubscriptionService()
-        countries_price, _ = await subscription_service.get_countries_price_by_uuids(
-            selected_countries,
-            db,
-            promo_group_id=db_user.promo_group_id,
-        )
-    except AttributeError:
-        logger.warning('Используем fallback функцию для расчета цен стран')
-        countries_price, _ = await get_countries_price_by_uuids_fallback(
-            selected_countries,
-            db,
-            promo_group_id=db_user.promo_group_id,
-        )
-
     data['countries'] = selected_countries
-    data['total_price'] = base_price + countries_price
+
+    # Вычисляем цену через PricingEngine с актуальными FSM-данными
+    pricing_result = await pricing_engine.calculate_classic_new_subscription_price(
+        db,
+        data['period_days'],
+        list(selected_countries),
+        data.get('traffic_gb', 0) or 0,
+        data.get('devices', settings.DEFAULT_DEVICE_LIMIT),
+        user=db_user,
+    )
+    data['total_price'] = pricing_result.final_total
     await state.set_data(data)
 
     await callback.message.edit_reply_markup(
@@ -700,7 +693,7 @@ async def handle_add_country_to_subscription(
     total_price = 0
     subscription = db_user.subscription
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    servers_discount_percent = _get_addon_discount_percent_for_user(
+    servers_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'servers',
         period_hint_days,
@@ -808,12 +801,16 @@ async def confirm_add_countries_to_subscription(
         await callback.answer('⚠️ Изменения не обнаружены', show_alert=True)
         return
 
+    # TOCTOU protection: lock user row before reading discount and charging balance
+    db_user = await lock_user_for_pricing(db, db_user.id)
+    subscription = db_user.subscription
+
     total_price = 0
     new_countries_names = []
     removed_countries_names = []
 
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    servers_discount_percent = _get_addon_discount_percent_for_user(
+    servers_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'servers',
         period_hint_days,

app/handlers/subscription/devices.py

@@ -7,7 +7,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.config import settings
 from app.database.crud.transaction import create_transaction
-from app.database.crud.user import subtract_user_balance
+from app.database.crud.user import lock_user_for_pricing, subtract_user_balance
 from app.database.models import Subscription, TransactionType, User
 from app.keyboards.inline import (
     get_app_selection_keyboard,
@@ -21,6 +21,7 @@ from app.keyboards.inline import (
     get_specific_app_keyboard,
 )
 from app.localization.texts import get_texts
+from app.services.pricing_engine import PricingEngine
 from app.services.remnawave_service import RemnaWaveService
 from app.services.subscription_service import SubscriptionService
 from app.services.user_cart_service import user_cart_service
@@ -33,7 +34,6 @@ from app.utils.subscription_utils import (
 )
 
 from .common import (
-    _get_addon_discount_percent_for_user,
     _get_period_hint_from_subscription,
     get_apps_for_platform_async,
     get_device_name,
@@ -174,7 +174,7 @@ async def handle_change_devices(callback: types.CallbackQuery, db_user: User, db
     current_devices = subscription.device_limit
 
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    devices_discount_percent = _get_addon_discount_percent_for_user(
+    devices_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'devices',
         period_hint_days,
@@ -325,7 +325,7 @@ async def confirm_change_devices(callback: types.CallbackQuery, db_user: User, d
             days_left = max(1, (subscription.end_date - now).days)
             period_hint_days = days_left
 
-            devices_discount_percent = _get_addon_discount_percent_for_user(
+            devices_discount_percent = PricingEngine.get_addon_discount_percent(
                 db_user,
                 'devices',
                 period_hint_days,
@@ -345,7 +345,7 @@ async def confirm_change_devices(callback: types.CallbackQuery, db_user: User, d
             days_left = max(1, (subscription.end_date - now).days)
             period_hint_days = days_left
 
-            devices_discount_percent = _get_addon_discount_percent_for_user(
+            devices_discount_percent = PricingEngine.get_addon_discount_percent(
                 db_user,
                 'devices',
                 period_hint_days,
@@ -492,7 +492,8 @@ async def confirm_change_devices(callback: types.CallbackQuery, db_user: User, d
 async def execute_change_devices(callback: types.CallbackQuery, db_user: User, db: AsyncSession):
     callback_parts = callback.data.split('_')
     new_devices_count = int(callback_parts[3])
-    price = int(callback_parts[4])
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
 
     texts = get_texts(db_user.language)
     subscription = db_user.subscription
@@ -514,12 +515,15 @@ async def execute_change_devices(callback: types.CallbackQuery, db_user: User, d
                 show_alert=True,
             )
             return
+        price_per_device = tariff_device_price
     elif not settings.is_devices_selection_enabled():
         await callback.answer(
             texts.t('DEVICES_SELECTION_DISABLED', '⚠️ Изменение количества устройств недоступно'),
             show_alert=True,
         )
         return
+    else:
+        price_per_device = settings.PRICE_PER_DEVICE
 
     # Проверяем минимальное количество устройств на тарифе
     tariff_min_devices = (getattr(tariff, 'device_limit', 1) or 1) if tariff else 1
@@ -533,6 +537,33 @@ async def execute_change_devices(callback: types.CallbackQuery, db_user: User, d
         )
         return
 
+    # Recompute price under lock (callback-baked value may be stale)
+    devices_difference = new_devices_count - current_devices
+    if devices_difference > 0:
+        if tariff:
+            chargeable_devices = devices_difference
+        elif current_devices < settings.DEFAULT_DEVICE_LIMIT:
+            free_devices = settings.DEFAULT_DEVICE_LIMIT - current_devices
+            chargeable_devices = max(0, devices_difference - free_devices)
+        else:
+            chargeable_devices = devices_difference
+
+        devices_price_per_month = chargeable_devices * price_per_device
+        days_left = max(1, (subscription.end_date - datetime.now(UTC)).days)
+        devices_discount_percent = PricingEngine.get_addon_discount_percent(
+            db_user,
+            'devices',
+            days_left,
+        )
+        discounted_per_month, _ = apply_percentage_discount(
+            devices_price_per_month,
+            devices_discount_percent,
+        )
+        price = int(discounted_per_month * days_left / 30)
+        price = max(100, price)
+    else:
+        price = 0
+
     try:
         if price > 0:
             success = await subtract_user_balance(
@@ -1148,6 +1179,9 @@ async def confirm_add_devices(callback: types.CallbackQuery, db_user: User, db:
 
     devices_price_per_month = devices_count * price_per_device
 
+    # TOCTOU: lock user row before reading promo/discount state
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
     # Проверяем является ли тариф суточным
     is_daily_tariff = tariff and getattr(tariff, 'is_daily', False)
 
@@ -1157,7 +1191,7 @@ async def confirm_add_devices(callback: types.CallbackQuery, db_user: User, db:
         days_left = max(1, (subscription.end_date - now).days)
         period_hint_days = days_left
 
-        devices_discount_percent = _get_addon_discount_percent_for_user(
+        devices_discount_percent = PricingEngine.get_addon_discount_percent(
             db_user,
             'devices',
             period_hint_days,
@@ -1177,7 +1211,7 @@ async def confirm_add_devices(callback: types.CallbackQuery, db_user: User, db:
         days_left = max(1, (subscription.end_date - now).days)
         period_hint_days = days_left
 
-        devices_discount_percent = _get_addon_discount_percent_for_user(
+        devices_discount_percent = PricingEngine.get_addon_discount_percent(
             db_user,
             'devices',
             period_hint_days,

app/handlers/subscription/pricing.py

@@ -4,18 +4,15 @@ from typing import Any
 
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.config import PERIOD_PRICES, settings
+from app.config import settings
 from app.database.models import User
 from app.utils.pricing_utils import (
-    apply_percentage_discount,
-    calculate_months_from_days,
     format_period_description,
-    validate_pricing_calculation,
 )
 from app.utils.timezone import format_local_datetime
 
-from .common import _apply_discount_to_monthly_component, _apply_promo_offer_discount, logger
-from .countries import _get_available_countries, _get_countries_info, get_countries_price_by_uuids_fallback
+from .common import logger
+from .countries import _get_available_countries, _get_countries_info
 from .devices import get_current_devices_count
 from .promo import _build_promo_group_discount_text, _get_promo_offer_hint
 
@@ -25,82 +22,18 @@ async def _prepare_subscription_summary(
     data: dict[str, Any],
     texts,
 ) -> tuple[str, dict[str, Any]]:
+    from app.database.database import AsyncSessionLocal
+    from app.services.pricing_engine import PricingEngine, pricing_engine
+
     summary_data = dict(data)
 
     if 'period_days' not in summary_data:
         raise KeyError('period_days missing from subscription data — FSM state likely expired')
 
-    countries = await _get_available_countries(db_user.promo_group_id)
-
-    months_in_period = calculate_months_from_days(summary_data['period_days'])
-    period_display = format_period_description(summary_data['period_days'], db_user.language)
-
-    base_price_original = PERIOD_PRICES.get(summary_data['period_days'], 0)
-    period_discount_percent = db_user.get_promo_discount(
-        'period',
-        summary_data['period_days'],
-    )
-    base_price, base_discount_total = apply_percentage_discount(
-        base_price_original,
-        period_discount_percent,
-    )
-
-    if settings.is_traffic_fixed():
-        traffic_limit = settings.get_fixed_traffic_limit()
-        traffic_price_per_month = settings.get_traffic_price(traffic_limit)
-        final_traffic_gb = traffic_limit
-    else:
-        traffic_gb = summary_data.get('traffic_gb', 0)
-        traffic_price_per_month = settings.get_traffic_price(traffic_gb)
-        final_traffic_gb = traffic_gb
-
-    traffic_discount_percent = db_user.get_promo_discount(
-        'traffic',
-        summary_data['period_days'],
-    )
-    traffic_component = _apply_discount_to_monthly_component(
-        traffic_price_per_month,
-        traffic_discount_percent,
-        months_in_period,
-    )
-    total_traffic_price = traffic_component['total']
-
-    countries_price_per_month = 0
-    selected_countries_names: list[str] = []
-    selected_server_prices: list[int] = []
-    server_monthly_prices: list[int] = []
-
-    selected_country_ids = set(summary_data.get('countries', []))
-    for country in countries:
-        if country['uuid'] in selected_country_ids:
-            server_price_per_month = country['price_kopeks']
-            countries_price_per_month += server_price_per_month
-            selected_countries_names.append(html.escape(country['name']))
-            server_monthly_prices.append(server_price_per_month)
-
-    servers_discount_percent = db_user.get_promo_discount(
-        'servers',
-        summary_data['period_days'],
-    )
-    total_countries_price = 0
-    total_servers_discount = 0
-    discounted_servers_price_per_month = 0
-
-    for server_price_per_month in server_monthly_prices:
-        discounted_per_month, discount_per_month = apply_percentage_discount(
-            server_price_per_month,
-            servers_discount_percent,
-        )
-        total_price_for_server = discounted_per_month * months_in_period
-        total_discount_for_server = discount_per_month * months_in_period
-
-        discounted_servers_price_per_month += discounted_per_month
-        total_countries_price += total_price_for_server
-        total_servers_discount += total_discount_for_server
-        selected_server_prices.append(total_price_for_server)
+    period_days = summary_data['period_days']
 
+    # --- Resolve device limit (same logic as before) ---
     devices_selection_enabled = settings.is_devices_selection_enabled()
-    forced_disabled_limit: int | None = None
     if devices_selection_enabled:
         devices_selected = summary_data.get('devices', settings.DEFAULT_DEVICE_LIMIT)
     else:
@@ -109,54 +42,75 @@ async def _prepare_subscription_summary(
             devices_selected = settings.DEFAULT_DEVICE_LIMIT
         else:
             devices_selected = forced_disabled_limit
-
     summary_data['devices'] = devices_selected
-    additional_devices = max(0, devices_selected - settings.DEFAULT_DEVICE_LIMIT)
-    devices_price_per_month = additional_devices * settings.PRICE_PER_DEVICE
-    devices_discount_percent = db_user.get_promo_discount(
-        'devices',
-        summary_data['period_days'],
-    )
-    devices_component = _apply_discount_to_monthly_component(
-        devices_price_per_month,
-        devices_discount_percent,
-        months_in_period,
-    )
-    total_devices_price = devices_component['total']
 
-    total_price = base_price + total_traffic_price + total_countries_price + total_devices_price
+    # --- Resolve traffic ---
+    if settings.is_traffic_fixed():
+        final_traffic_gb = settings.get_fixed_traffic_limit()
+    else:
+        final_traffic_gb = summary_data.get('traffic_gb', 0)
 
+    # --- Resolve connected squads ---
+    connected_squads = list(summary_data.get('countries', []))
+
+    # --- Delegate pricing to PricingEngine ---
+    async with AsyncSessionLocal() as db:
+        pricing = await pricing_engine.calculate_classic_new_subscription_price(
+            db,
+            period_days,
+            connected_squads,
+            final_traffic_gb,
+            devices_selected,
+            user=db_user,
+        )
+
+    # --- Build legacy dict from PricingEngine result ---
+    details = PricingEngine.classic_pricing_to_purchase_details(pricing)
+    bd = pricing.breakdown
+
+    months_in_period = details['months_in_period']
+    base_price = details['base_price']
+    base_price_original = details['base_price_original']
+    base_discount_total = details['base_discount_total']
+    period_discount_percent = details['base_discount_percent']
+    traffic_price_per_month = details['traffic_price_per_month']
+    traffic_discount_percent = details['traffic_discount_percent']
+    traffic_discount_total = details['traffic_discount_total']
+    total_traffic_price = details['total_traffic_price']
+    servers_price_per_month = details['servers_price_per_month']
+    servers_discount_percent = details['servers_discount_percent']
+    servers_discount_total = details['servers_discount_total']
+    total_servers_price = details['total_servers_price']
+    devices_price_per_month = details['devices_price_per_month']
+    devices_discount_percent = details['devices_discount_percent']
+    devices_discount_total = details['devices_discount_total']
+    total_devices_price = details['total_devices_price']
+
+    # Compute discounted per-month values (not in classic_pricing_to_purchase_details)
+    traffic_discounted_per_month = PricingEngine.apply_discount(traffic_price_per_month, traffic_discount_percent)
+    servers_discounted_per_month = PricingEngine.apply_discount(servers_price_per_month, servers_discount_percent)
+    devices_discounted_per_month = PricingEngine.apply_discount(devices_price_per_month, devices_discount_percent)
     discounted_monthly_additions = (
-        traffic_component['discounted_per_month']
-        + discounted_servers_price_per_month
-        + devices_component['discounted_per_month']
+        traffic_discounted_per_month + servers_discounted_per_month + devices_discounted_per_month
     )
 
-    is_valid = validate_pricing_calculation(
-        base_price,
-        discounted_monthly_additions,
-        months_in_period,
-        total_price,
-    )
-
-    if not is_valid:
-        raise ValueError('Subscription price calculation validation failed')
-
-    original_total_price = total_price
-    promo_offer_component = _apply_promo_offer_discount(db_user, total_price)
-    if promo_offer_component['discount'] > 0:
-        total_price = promo_offer_component['discounted']
+    # --- Promo offer discount (already computed by PricingEngine) ---
+    promo_offer_discount = pricing.promo_offer_discount
+    offer_pct = bd.get('offer_discount_pct', 0)
+    # subtotal before promo offer = final_total + promo_offer_discount
+    subtotal_before_offer = pricing.final_total + promo_offer_discount
+    total_price = pricing.final_total
 
     summary_data['total_price'] = total_price
-    if promo_offer_component['discount'] > 0:
-        summary_data['promo_offer_discount_percent'] = promo_offer_component['percent']
-        summary_data['promo_offer_discount_value'] = promo_offer_component['discount']
-        summary_data['total_price_before_promo_offer'] = original_total_price
+    if promo_offer_discount > 0:
+        summary_data['promo_offer_discount_percent'] = offer_pct
+        summary_data['promo_offer_discount_value'] = promo_offer_discount
+        summary_data['total_price_before_promo_offer'] = subtotal_before_offer
     else:
         summary_data.pop('promo_offer_discount_percent', None)
         summary_data.pop('promo_offer_discount_value', None)
         summary_data.pop('total_price_before_promo_offer', None)
-    summary_data['server_prices_for_period'] = selected_server_prices
+    summary_data['server_prices_for_period'] = details['servers_individual_prices']
     summary_data['months_in_period'] = months_in_period
     summary_data['base_price'] = base_price
     summary_data['base_price_original'] = base_price_original
@@ -164,24 +118,27 @@ async def _prepare_subscription_summary(
     summary_data['base_discount_total'] = base_discount_total
     summary_data['final_traffic_gb'] = final_traffic_gb
     summary_data['traffic_price_per_month'] = traffic_price_per_month
-    summary_data['traffic_discount_percent'] = traffic_component['discount_percent']
-    summary_data['traffic_discount_total'] = traffic_component['discount_total']
-    summary_data['traffic_discounted_price_per_month'] = traffic_component['discounted_per_month']
+    summary_data['traffic_discount_percent'] = traffic_discount_percent
+    summary_data['traffic_discount_total'] = traffic_discount_total
+    summary_data['traffic_discounted_price_per_month'] = traffic_discounted_per_month
     summary_data['total_traffic_price'] = total_traffic_price
-    summary_data['servers_price_per_month'] = countries_price_per_month
-    summary_data['countries_price_per_month'] = countries_price_per_month
+    summary_data['servers_price_per_month'] = servers_price_per_month
+    summary_data['countries_price_per_month'] = servers_price_per_month
     summary_data['servers_discount_percent'] = servers_discount_percent
-    summary_data['servers_discount_total'] = total_servers_discount
-    summary_data['servers_discounted_price_per_month'] = discounted_servers_price_per_month
-    summary_data['total_servers_price'] = total_countries_price
-    summary_data['total_countries_price'] = total_countries_price
+    summary_data['servers_discount_total'] = servers_discount_total
+    summary_data['servers_discounted_price_per_month'] = servers_discounted_per_month
+    summary_data['total_servers_price'] = total_servers_price
+    summary_data['total_countries_price'] = total_servers_price
     summary_data['devices_price_per_month'] = devices_price_per_month
-    summary_data['devices_discount_percent'] = devices_component['discount_percent']
-    summary_data['devices_discount_total'] = devices_component['discount_total']
-    summary_data['devices_discounted_price_per_month'] = devices_component['discounted_per_month']
+    summary_data['devices_discount_percent'] = devices_discount_percent
+    summary_data['devices_discount_total'] = devices_discount_total
+    summary_data['devices_discounted_price_per_month'] = devices_discounted_per_month
     summary_data['total_devices_price'] = total_devices_price
     summary_data['discounted_monthly_additions'] = discounted_monthly_additions
 
+    # --- Build display text ---
+    period_display = format_period_description(period_days, db_user.language)
+
     if settings.is_traffic_fixed():
         if final_traffic_gb == 0:
             traffic_display = 'Безлимитный'
@@ -192,6 +149,13 @@ async def _prepare_subscription_summary(
     else:
         traffic_display = f'{summary_data.get("traffic_gb", 0)} ГБ'
 
+    # Resolve country display names (still needed for the summary text)
+    countries = await _get_available_countries(db_user.promo_group_id)
+    selected_country_ids = set(connected_squads)
+    selected_countries_names: list[str] = [
+        html.escape(country['name']) for country in countries if country['uuid'] in selected_country_ids
+    ]
+
     details_lines = []
 
     # Добавляем строку базового периода только если цена не равна 0
@@ -212,40 +176,34 @@ async def _prepare_subscription_summary(
             f'- Трафик: {texts.format_price(traffic_price_per_month)}/мес × {months_in_period}'
             f' = {texts.format_price(total_traffic_price)}'
         )
-        if traffic_component['discount_total'] > 0:
-            traffic_line += (
-                f' (скидка {traffic_component["discount_percent"]}%:'
-                f' -{texts.format_price(traffic_component["discount_total"])})'
-            )
+        if traffic_discount_total > 0:
+            traffic_line += f' (скидка {traffic_discount_percent}%: -{texts.format_price(traffic_discount_total)})'
         details_lines.append(traffic_line)
-    if total_countries_price > 0:
+    if total_servers_price > 0:
         servers_line = (
-            f'- Серверы: {texts.format_price(countries_price_per_month)}/мес × {months_in_period}'
-            f' = {texts.format_price(total_countries_price)}'
+            f'- Серверы: {texts.format_price(servers_price_per_month)}/мес × {months_in_period}'
+            f' = {texts.format_price(total_servers_price)}'
         )
-        if total_servers_discount > 0:
-            servers_line += f' (скидка {servers_discount_percent}%: -{texts.format_price(total_servers_discount)})'
+        if servers_discount_total > 0:
+            servers_line += f' (скидка {servers_discount_percent}%: -{texts.format_price(servers_discount_total)})'
         details_lines.append(servers_line)
     if devices_selection_enabled and total_devices_price > 0:
         devices_line = (
             f'- Доп. устройства: {texts.format_price(devices_price_per_month)}/мес × {months_in_period}'
             f' = {texts.format_price(total_devices_price)}'
         )
-        if devices_component['discount_total'] > 0:
-            devices_line += (
-                f' (скидка {devices_component["discount_percent"]}%:'
-                f' -{texts.format_price(devices_component["discount_total"])})'
-            )
+        if devices_discount_total > 0:
+            devices_line += f' (скидка {devices_discount_percent}%: -{texts.format_price(devices_discount_total)})'
         details_lines.append(devices_line)
 
-    if promo_offer_component['discount'] > 0:
+    if promo_offer_discount > 0:
         details_lines.append(
             texts.t(
                 'SUBSCRIPTION_SUMMARY_PROMO_DISCOUNT',
                 '- Промо-предложение: -{amount} ({percent}% дополнительно)',
             ).format(
-                amount=texts.format_price(promo_offer_component['discount']),
-                percent=promo_offer_component['percent'],
+                amount=texts.format_price(promo_offer_discount),
+                percent=offer_pct,
             )
         )
 
@@ -309,114 +267,21 @@ async def get_subscription_cost(subscription, db: AsyncSession) -> int:
         if subscription.is_trial:
             return 0
 
-        from app.config import settings
-        from app.database.crud.tariff import get_tariff_by_id
-        from app.services.subscription_service import SubscriptionService
-
-        subscription_service = SubscriptionService()
+        from app.services.pricing_engine import pricing_engine
 
         try:
             owner = subscription.user
         except AttributeError:
             owner = None
 
-        promo_group_id = getattr(owner, 'promo_group_id', None) if owner else None
-
-        # В тарифном режиме цена тарифа уже включает серверы и трафик
-        tariff = None
-        tariff_price_found = False
-        if settings.is_tariffs_mode() and subscription.tariff_id:
-            tariff = await get_tariff_by_id(db, subscription.tariff_id)
-            if tariff and tariff.period_prices:
-                base_cost_original = tariff.period_prices.get('30', 0) or tariff.period_prices.get(30, 0)
-                if base_cost_original > 0:
-                    tariff_price_found = True
-
-        if not tariff_price_found:
-            base_cost_original = PERIOD_PRICES.get(30, 0)
-
-        if tariff_price_found:
-            # Тарифный режим: серверы и трафик включены в цену.
-            # Порядок: база + устройства → скидка на полную сумму (как в calculate_renewal_price).
-            from app.utils.promo_offer import get_user_active_promo_discount_percent
-
-            original_price = base_cost_original
-
-            tariff_device_limit = tariff.device_limit if tariff.device_limit is not None else 0
-            device_limit = subscription.device_limit if subscription.device_limit is not None else tariff_device_limit
-            extra_devices = max(0, device_limit - tariff_device_limit)
-            device_price_per_unit = (
-                tariff.device_price_kopeks
-                if tariff and tariff.device_price_kopeks is not None
-                else settings.PRICE_PER_DEVICE
-            )
-            devices_price = extra_devices * device_price_per_unit
-            original_price += devices_price
-
-            # Скидка промогруппы на полную сумму (база + устройства)
-            period_discount_percent = 0
-            if owner:
-                try:
-                    period_discount_percent = owner.get_promo_discount('period', 30)
-                except AttributeError:
-                    pass
-            discount_total = original_price * period_discount_percent // 100
-            total_cost = original_price - discount_total
-
-            # Promo-offer скидка (временная)
-            promo_offer_percent = get_user_active_promo_discount_percent(owner)
-            if promo_offer_percent > 0:
-                promo_offer_discount = total_cost * promo_offer_percent // 100
-                total_cost = total_cost - promo_offer_discount
-        else:
-            # Классический режим: серверы + трафик + устройства считаются отдельно
-            period_discount_percent = 0
-            if owner:
-                try:
-                    period_discount_percent = owner.get_promo_discount('period', 30)
-                except AttributeError:
-                    period_discount_percent = 0
-
-            base_cost, _ = apply_percentage_discount(
-                base_cost_original,
-                period_discount_percent,
-            )
-
-            try:
-                servers_cost, _ = await subscription_service.get_countries_price_by_uuids(
-                    subscription.connected_squads,
-                    db,
-                    promo_group_id=promo_group_id,
-                )
-            except AttributeError:
-                servers_cost, _ = await get_countries_price_by_uuids_fallback(
-                    subscription.connected_squads,
-                    db,
-                    promo_group_id=promo_group_id,
-                )
-
-            traffic_cost = settings.get_traffic_price(subscription.traffic_limit_gb)
-            device_limit = subscription.device_limit
-            if device_limit is None:
-                if settings.is_devices_selection_enabled():
-                    device_limit = settings.DEFAULT_DEVICE_LIMIT
-                else:
-                    forced_limit = settings.get_disabled_mode_device_limit()
-                    if forced_limit is None:
-                        device_limit = settings.DEFAULT_DEVICE_LIMIT
-                    else:
-                        device_limit = forced_limit
-
-            devices_cost = max(0, (device_limit or 0) - settings.DEFAULT_DEVICE_LIMIT) * settings.PRICE_PER_DEVICE
-
-            total_cost = base_cost + servers_cost + traffic_cost + devices_cost
-
-        logger.info('Месячная стоимость подписки', subscription_id=subscription.id, total_cost_kopeks=total_cost)
+        result = await pricing_engine.calculate_renewal_price(db, subscription, 30, user=owner)
+        total_cost = result.final_total
 
+        logger.info('Monthly subscription cost', subscription_id=subscription.id, total_cost_kopeks=total_cost)
         return total_cost
 
     except Exception as e:
-        logger.error('Ошибка расчета стоимости подписки', error=e)
+        logger.error('Error calculating subscription cost', error=e)
         return 0
 
 

app/handlers/subscription/purchase.py

@@ -9,7 +9,7 @@ from aiogram.fsm.context import FSMContext
 from aiogram.types import InaccessibleMessage, InlineKeyboardButton, InlineKeyboardMarkup
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.config import PERIOD_PRICES, settings
+from app.config import settings
 from app.database.crud.subscription import (
     create_paid_subscription,
     create_pending_trial_subscription,
@@ -37,6 +37,7 @@ from app.keyboards.inline import (
 )
 from app.localization.texts import get_texts
 from app.services.admin_notification_service import AdminNotificationService
+from app.services.pricing_engine import pricing_engine
 from app.services.remnawave_service import RemnaWaveConfigurationError
 from app.services.subscription_checkout_service import (
     clear_subscription_checkout_draft,
@@ -99,7 +100,6 @@ from app.handlers.simple_subscription import (
 from app.states import SubscriptionStates
 from app.utils.price_display import PriceInfo, format_price_text
 from app.utils.pricing_utils import (
-    apply_percentage_discount,
     calculate_months_from_days,
     format_period_description,
 )
@@ -343,8 +343,23 @@ async def show_subscription_info(callback: types.CallbackQuery, db_user: User, d
                 ]
 
                 if is_daily:
-                    # Для суточного тарифа показываем цену и прогресс-бар
-                    daily_price = getattr(tariff, 'daily_price_kopeks', 0) / 100
+                    # Для суточного тарифа показываем цену с учётом скидки промогруппы + promo-offer
+                    raw_daily_kopeks = getattr(tariff, 'daily_price_kopeks', 0)
+                    promo_group = (
+                        db_user.get_primary_promo_group() if hasattr(db_user, 'get_primary_promo_group') else None
+                    )
+                    daily_group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+                    from app.services.pricing_engine import PricingEngine
+                    from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+                    daily_offer_pct = get_user_active_promo_discount_percent(db_user)
+                    if daily_group_pct > 0 or daily_offer_pct > 0:
+                        daily_kopeks, _, _ = PricingEngine.apply_stacked_discounts(
+                            raw_daily_kopeks, daily_group_pct, daily_offer_pct
+                        )
+                    else:
+                        daily_kopeks = raw_daily_kopeks
+                    daily_price = daily_kopeks / 100
                     tariff_info_lines.append(f'Цена: {daily_price:.2f} ₽/день')
 
                     # Прогресс-бар до следующего списания
@@ -1735,9 +1750,11 @@ async def confirm_extend_subscription(callback: types.CallbackQuery, db_user: Us
         await callback.answer('⚠ У вас нет активной подписки', show_alert=True)
         return
 
+    from app.database.crud.user import lock_user_for_pricing
     from app.services.pricing_engine import pricing_engine
     from app.services.subscription_renewal_service import SubscriptionRenewalChargeError, SubscriptionRenewalService
 
+    db_user = await lock_user_for_pricing(db, db_user.id)
     months_in_period = calculate_months_from_days(days)
 
     try:
@@ -1884,7 +1901,7 @@ async def confirm_extend_subscription(callback: types.CallbackQuery, db_user: Us
     await callback.answer()
 
 
-async def select_period(callback: types.CallbackQuery, state: FSMContext, db_user: User):
+async def select_period(callback: types.CallbackQuery, state: FSMContext, db_user: User, db: AsyncSession):
     period_days = int(callback.data.split('_')[1])
     texts = get_texts(db_user.language)
 
@@ -1894,18 +1911,23 @@ async def select_period(callback: types.CallbackQuery, state: FSMContext, db_use
         await callback.answer(texts.t('PERIOD_NOT_AVAILABLE', '❌ Этот период больше недоступен'), show_alert=True)
         return
 
-    # Получаем цену с защитой от KeyError
-    period_price = PERIOD_PRICES.get(period_days, 0)
-
     data = await state.get_data()
     data['period_days'] = period_days
-    data['total_price'] = period_price
 
     if settings.is_traffic_fixed():
-        fixed_traffic_price = settings.get_traffic_price(settings.get_fixed_traffic_limit())
-        data['total_price'] += fixed_traffic_price
         data['traffic_gb'] = settings.get_fixed_traffic_limit()
 
+    # Вычисляем промежуточную цену через PricingEngine (countries/devices ещё не выбраны)
+    pricing_result = await pricing_engine.calculate_classic_new_subscription_price(
+        db,
+        period_days,
+        list(data.get('countries', [])),
+        data.get('traffic_gb', 0) or 0,
+        data.get('devices', settings.DEFAULT_DEVICE_LIMIT),
+        user=db_user,
+    )
+    data['total_price'] = pricing_result.final_total
+
     await state.set_data(data)
 
     if settings.is_traffic_selectable():
@@ -1958,7 +1980,7 @@ async def select_period(callback: types.CallbackQuery, state: FSMContext, db_use
         await callback.answer()
 
 
-async def select_devices(callback: types.CallbackQuery, state: FSMContext, db_user: User):
+async def select_devices(callback: types.CallbackQuery, state: FSMContext, db_user: User, db: AsyncSession):
     texts = get_texts(db_user.language)
 
     if not settings.is_devices_selection_enabled():
@@ -1980,27 +2002,27 @@ async def select_devices(callback: types.CallbackQuery, state: FSMContext, db_us
 
     data = await state.get_data()
 
-    # Получаем цену периода с защитой от KeyError
     period_days = data.get('period_days')
-    if not period_days or period_days not in PERIOD_PRICES:
+    if not period_days:
         await callback.answer(
             texts.t('PERIOD_NOT_AVAILABLE', '❌ Период больше недоступен, начните заново'), show_alert=True
         )
         return
 
-    base_price = PERIOD_PRICES.get(period_days, 0) + settings.get_traffic_price(data.get('traffic_gb', 0))
-
-    countries = await _get_available_countries(db_user.promo_group_id)
-    # Проверяем, что ключ 'countries' существует в данных перед доступом к нему
-    selected_countries = data.get('countries', [])
-    countries_price = sum(c['price_kopeks'] for c in countries if c['uuid'] in selected_countries)
-
-    devices_price = max(0, devices - settings.DEFAULT_DEVICE_LIMIT) * settings.PRICE_PER_DEVICE
-
     previous_devices = data.get('devices', settings.DEFAULT_DEVICE_LIMIT)
 
     data['devices'] = devices
-    data['total_price'] = base_price + countries_price + devices_price
+
+    # Вычисляем цену через PricingEngine с актуальными FSM-данными
+    pricing_result = await pricing_engine.calculate_classic_new_subscription_price(
+        db,
+        period_days,
+        list(data.get('countries', [])),
+        data.get('traffic_gb', 0) or 0,
+        devices,
+        user=db_user,
+    )
+    data['total_price'] = pricing_result.final_total
     await state.set_data(data)
 
     if devices != previous_devices:
@@ -2049,8 +2071,6 @@ async def confirm_purchase(callback: types.CallbackQuery, state: FSMContext, db_
     await save_subscription_checkout_draft(db_user.id, dict(data))
     resume_callback = 'subscription_resume_checkout' if should_offer_checkout_resume(db_user, True) else None
 
-    countries = await _get_available_countries(db_user.promo_group_id)
-
     period_days = data.get('period_days')
     if period_days is None:
         await callback.message.edit_text(
@@ -2059,62 +2079,8 @@ async def confirm_purchase(callback: types.CallbackQuery, state: FSMContext, db_
         )
         await callback.answer()
         return
-    months_in_period = data.get('months_in_period', calculate_months_from_days(period_days))
-
-    # Всегда пересчитываем base_price из PERIOD_PRICES для безопасности
-    # (не доверяем кэшированным значениям из FSM данных)
-    base_price_original = PERIOD_PRICES.get(period_days, 0)
-    base_discount_percent = db_user.get_promo_discount(
-        'period',
-        period_days,
-    )
-    base_price, base_discount_total = apply_percentage_discount(
-        base_price_original,
-        base_discount_percent,
-    )
-    server_prices = data.get('server_prices_for_period', [])
-
-    if not server_prices:
-        countries_price_per_month = 0
-        per_month_prices: list[int] = []
-        for country in countries:
-            # Проверяем, что ключ 'countries' существует в данных перед доступом к нему
-            selected_countries = data.get('countries', [])
-            if country['uuid'] in selected_countries:
-                server_price_per_month = country['price_kopeks']
-                countries_price_per_month += server_price_per_month
-                per_month_prices.append(server_price_per_month)
-
-        servers_discount_percent = db_user.get_promo_discount(
-            'servers',
-            period_days,
-        )
-        total_servers_price = 0
-        total_servers_discount = 0
-        discounted_servers_price_per_month = 0
-        server_prices = []
-
-        for server_price_per_month in per_month_prices:
-            discounted_per_month, discount_per_month = apply_percentage_discount(
-                server_price_per_month,
-                servers_discount_percent,
-            )
-            total_price_for_server = discounted_per_month * months_in_period
-            total_discount_for_server = discount_per_month * months_in_period
-
-            discounted_servers_price_per_month += discounted_per_month
-            total_servers_price += total_price_for_server
-            total_servers_discount += total_discount_for_server
-            server_prices.append(total_price_for_server)
-
-        total_countries_price = total_servers_price
-    else:
-        total_countries_price = data.get('total_servers_price', sum(server_prices))
-        countries_price_per_month = data.get('servers_price_per_month', 0)
-        discounted_servers_price_per_month = data.get('servers_discounted_price_per_month', countries_price_per_month)
-        total_servers_discount = data.get('servers_discount_total', 0)
-        servers_discount_percent = data.get('servers_discount_percent', 0)
 
+    # --- Resolve device limit (needed for PricingEngine and subscription creation) ---
     devices_selection_enabled = settings.is_devices_selection_enabled()
     forced_disabled_limit: int | None = None
     if devices_selection_enabled:
@@ -2126,95 +2092,42 @@ async def confirm_purchase(callback: types.CallbackQuery, state: FSMContext, db_
         else:
             devices_selected = forced_disabled_limit
 
-    additional_devices = max(0, devices_selected - settings.DEFAULT_DEVICE_LIMIT)
-    devices_price_per_month = data.get('devices_price_per_month', additional_devices * settings.PRICE_PER_DEVICE)
-
-    devices_discount_percent = 0
-    discounted_devices_price_per_month = 0
-    devices_discount_total = 0
-    total_devices_price = 0
-
-    if devices_selection_enabled and additional_devices > 0:
-        if 'devices_discount_percent' in data:
-            devices_discount_percent = data.get('devices_discount_percent', 0)
-            discounted_devices_price_per_month = data.get('devices_discounted_price_per_month', devices_price_per_month)
-            devices_discount_total = data.get('devices_discount_total', 0)
-            total_devices_price = data.get('total_devices_price', discounted_devices_price_per_month * months_in_period)
-        else:
-            devices_discount_percent = db_user.get_promo_discount(
-                'devices',
-                period_days,
-            )
-            discounted_devices_price_per_month, discount_per_month = apply_percentage_discount(
-                devices_price_per_month,
-                devices_discount_percent,
-            )
-            devices_discount_total = discount_per_month * months_in_period
-            total_devices_price = discounted_devices_price_per_month * months_in_period
-
+    # --- Resolve traffic ---
     if settings.is_traffic_fixed():
         final_traffic_gb = settings.get_fixed_traffic_limit()
-        traffic_price_per_month = data.get('traffic_price_per_month', settings.get_traffic_price(final_traffic_gb))
     else:
-        final_traffic_gb = data.get('final_traffic_gb', data.get('traffic_gb'))
-        traffic_gb = data.get('traffic_gb')
-        if traffic_gb is not None:
-            traffic_price_per_month = data.get('traffic_price_per_month', settings.get_traffic_price(traffic_gb))
-        else:
-            traffic_price_per_month = data.get('traffic_price_per_month', 0)
+        final_traffic_gb = data.get('final_traffic_gb', data.get('traffic_gb', 0))
 
-    if 'traffic_discount_percent' in data:
-        traffic_discount_percent = data.get('traffic_discount_percent', 0)
-        discounted_traffic_price_per_month = data.get('traffic_discounted_price_per_month', traffic_price_per_month)
-        traffic_discount_total = data.get('traffic_discount_total', 0)
-        total_traffic_price = data.get('total_traffic_price', discounted_traffic_price_per_month * months_in_period)
-    else:
-        traffic_discount_percent = db_user.get_promo_discount(
-            'traffic',
-            period_days,
-        )
-        discounted_traffic_price_per_month, discount_per_month = apply_percentage_discount(
-            traffic_price_per_month,
-            traffic_discount_percent,
-        )
-        traffic_discount_total = discount_per_month * months_in_period
-        total_traffic_price = discounted_traffic_price_per_month * months_in_period
-
-    total_servers_price = data.get('total_servers_price', total_countries_price)
+    # --- Resolve connected squads ---
+    connected_squads = list(data.get('countries', []))
 
     cached_total_price = data.get('total_price', 0)
-    cached_promo_discount_value = data.get('promo_offer_discount_value', 0)
 
-    # Всегда пересчитываем monthly_additions из компонентов для безопасности
-    discounted_monthly_additions = (
-        discounted_traffic_price_per_month + discounted_servers_price_per_month + discounted_devices_price_per_month
+    # Lock user BEFORE promo-offer read to prevent TOCTOU
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # --- Delegate pricing to PricingEngine ---
+    from app.services.pricing_engine import PricingEngine, pricing_engine
+
+    pricing_result = await pricing_engine.calculate_classic_new_subscription_price(
+        db,
+        period_days,
+        connected_squads,
+        final_traffic_gb,
+        devices_selected,
+        user=db_user,
     )
+    details = PricingEngine.classic_pricing_to_purchase_details(pricing_result)
 
-    # Вычисляем ожидаемую цену до промо-скидки из компонентов
-    calculated_total_before_promo = base_price + (discounted_monthly_additions * months_in_period)
+    final_price = pricing_result.final_total
+    server_prices = details['servers_individual_prices']
+    months_in_period = details['months_in_period']
+    promo_offer_discount_value = pricing_result.promo_offer_discount
+    promo_offer_discount_percent = pricing_result.breakdown.get('offer_discount_pct', 0)
 
-    # Получаем сохраненную цену до промо-скидки или используем вычисленную
-    validation_total_price = data.get('total_price_before_promo_offer')
-    if validation_total_price is None and cached_promo_discount_value > 0:
-        validation_total_price = cached_total_price + cached_promo_discount_value
-    if validation_total_price is None:
-        validation_total_price = cached_total_price
-
-    current_promo_offer_percent = _get_promo_offer_discount_percent(db_user)
-    if current_promo_offer_percent > 0:
-        final_price, promo_offer_discount_value = apply_percentage_discount(
-            calculated_total_before_promo,
-            current_promo_offer_percent,
-        )
-        promo_offer_discount_percent = current_promo_offer_percent
-    else:
-        final_price = calculated_total_before_promo
-        promo_offer_discount_value = 0
-        promo_offer_discount_percent = 0
-
-    # Валидация: проверяем что cached_total_price соответствует ожидаемой финальной цене
-    # Блокируем только если цена ВЫРОСЛА (пользователь переплатит).
-    # Если цена снизилась (промо-скидка активировалась) — разрешаем покупку по новой цене.
+    # --- Price validation: block if price increased significantly vs cached FSM price ---
     price_difference = final_price - cached_total_price
     if price_difference > 0:
         max_allowed_increase = max(500, int(final_price * 0.05))  # 5% или минимум 5₽
@@ -2244,36 +2157,50 @@ async def confirm_purchase(callback: types.CallbackQuery, state: FSMContext, db_
             final_price=final_price / 100,
         )
 
-    # Используем пересчитанную цену
-    validation_total_price = calculated_total_before_promo
+    # --- Logging ---
+    base_price_original = details['base_price_original']
+    base_price = details['base_price']
+    base_discount_total = details['base_discount_total']
+    base_discount_percent = details['base_discount_percent']
 
     logger.info('Расчет покупки подписки на дней ( мес)', data=data['period_days'], months_in_period=months_in_period)
     base_log = f'   Период: {base_price_original / 100}₽'
     if base_discount_total and base_discount_total > 0:
         base_log += f' → {base_price / 100}₽ (скидка {base_discount_percent}%: -{base_discount_total / 100}₽)'
     logger.info(base_log)
-    if total_traffic_price > 0:
-        message = f'   Трафик: {traffic_price_per_month / 100}₽/мес × {months_in_period} = {total_traffic_price / 100}₽'
-        if traffic_discount_total > 0:
-            message += f' (скидка {traffic_discount_percent}%: -{traffic_discount_total / 100}₽)'
-        logger.info(message)
-    if total_servers_price > 0:
-        message = (
-            f'   Серверы: {countries_price_per_month / 100}₽/мес × {months_in_period} = {total_servers_price / 100}₽'
+    if details['total_traffic_price'] > 0:
+        traffic_msg = (
+            f'   Трафик: {details["traffic_price_per_month"] / 100}₽/мес'
+            f' × {months_in_period} = {details["total_traffic_price"] / 100}₽'
         )
-        if total_servers_discount > 0:
-            message += f' (скидка {servers_discount_percent}%: -{total_servers_discount / 100}₽)'
-        logger.info(message)
-    if total_devices_price > 0:
-        message = (
-            f'   Устройства: {devices_price_per_month / 100}₽/мес × {months_in_period} = {total_devices_price / 100}₽'
+        if details['traffic_discount_total'] > 0:
+            traffic_msg += (
+                f' (скидка {details["traffic_discount_percent"]}%: -{details["traffic_discount_total"] / 100}₽)'
+            )
+        logger.info(traffic_msg)
+    if details['total_servers_price'] > 0:
+        servers_msg = (
+            f'   Серверы: {details["servers_price_per_month"] / 100}₽/мес'
+            f' × {months_in_period} = {details["total_servers_price"] / 100}₽'
         )
-        if devices_discount_total > 0:
-            message += f' (скидка {devices_discount_percent}%: -{devices_discount_total / 100}₽)'
-        logger.info(message)
+        if details['servers_discount_total'] > 0:
+            servers_msg += (
+                f' (скидка {details["servers_discount_percent"]}%: -{details["servers_discount_total"] / 100}₽)'
+            )
+        logger.info(servers_msg)
+    if details['total_devices_price'] > 0:
+        devices_msg = (
+            f'   Устройства: {details["devices_price_per_month"] / 100}₽/мес'
+            f' × {months_in_period} = {details["total_devices_price"] / 100}₽'
+        )
+        if details['devices_discount_total'] > 0:
+            devices_msg += (
+                f' (скидка {details["devices_discount_percent"]}%: -{details["devices_discount_total"] / 100}₽)'
+            )
+        logger.info(devices_msg)
     if promo_offer_discount_value > 0:
         logger.info(
-            '🎯 Промо-предложение: -₽ (%)',
+            'Промо-предложение: -₽ (%)',
             promo_offer_discount_value=promo_offer_discount_value / 100,
             promo_offer_discount_percent=promo_offer_discount_percent,
         )
@@ -2953,7 +2880,16 @@ async def handle_toggle_daily_subscription_pause(callback: types.CallbackQuery,
 
     # При возобновлении проверяем баланс
     if needs_resume:
-        daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+        raw_daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+        from app.database.crud.user import lock_user_for_pricing
+        from app.services.pricing_engine import PricingEngine
+
+        db_user = await lock_user_for_pricing(db, db_user.id)
+        promo_group = PricingEngine.resolve_promo_group(db_user)
+        daily_group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+        daily_price = (
+            PricingEngine.apply_discount(raw_daily_price, daily_group_pct) if daily_group_pct > 0 else raw_daily_price
+        )
         if daily_price > 0 and db_user.balance_kopeks < daily_price:
             await callback.answer(
                 texts.t(
@@ -2966,7 +2902,6 @@ async def handle_toggle_daily_subscription_pause(callback: types.CallbackQuery,
 
     if needs_resume:
         # Списываем суточную оплату ДО активации (чтобы не было бесплатного дня)
-        daily_price = getattr(tariff, 'daily_price_kopeks', 0)
         if daily_price > 0 and is_inactive:
             from app.database.crud.user import subtract_user_balance
 
@@ -4147,13 +4082,14 @@ async def _extend_existing_subscription(
 ):
     """Продлевает существующую подписку."""
     from app.database.crud.transaction import create_transaction
-    from app.database.crud.user import subtract_user_balance
+    from app.database.crud.user import lock_user_for_pricing, subtract_user_balance
     from app.database.models import TransactionType
     from app.services.subscription_service import SubscriptionService
 
+    db_user = await lock_user_for_pricing(db, db_user.id)
     texts = get_texts(db_user.language)
 
-    # Рассчитываем цену подписки
+    # Рассчитываем цену подписки (group discounts per-category)
     subscription_params = {
         'period_days': period_days,
         'device_limit': device_limit,
@@ -4166,6 +4102,12 @@ async def _extend_existing_subscription(
         user=db_user,
         resolved_squad_uuid=squad_uuid,
     )
+
+    # PricingEngine already applies promo-offer discount inside calculate_classic_new_subscription_price.
+    # Only determine whether to consume the offer (zero it out after use).
+    from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+    consume_promo = get_user_active_promo_discount_percent(db_user) > 0
     logger.warning(
         'SIMPLE_SUBSCRIPTION_EXTEND_PRICE | user= | total= | base= | traffic= | devices= | servers= | discount= | device_limit',
         db_user_id=db_user.id,
@@ -4212,7 +4154,7 @@ async def _extend_existing_subscription(
             'device_limit': device_limit,
             'traffic_limit_gb': traffic_limit_gb,
             'squad_uuid': squad_uuid,
-            'consume_promo_offer': False,
+            'consume_promo_offer': consume_promo,
         }
 
         await user_cart_service.save_user_cart(db_user.id, cart_data)
@@ -4233,7 +4175,7 @@ async def _extend_existing_subscription(
         db_user,
         price_kopeks,
         f'Продление подписки на {period_days} дней',
-        consume_promo_offer=False,  # Простая покупка не использует промо-скидки
+        consume_promo_offer=consume_promo,
         mark_as_paid_subscription=True,
     )
 

app/handlers/subscription/tariff_purchase.py

@@ -79,9 +79,14 @@ def format_tariffs_list_text(
         discount_icon = ''
 
         if is_daily:
-            # Для суточных тарифов показываем цену за день
+            # Для суточных тарифов показываем цену за день с учётом скидки промогруппы
             daily_price = getattr(tariff, 'daily_price_kopeks', 0)
-            price_text = f'🔄 {format_price_kopeks(daily_price, compact=True)}/день'
+            if db_user:
+                group_pct, offer_pct, daily_discount = _get_user_period_discount(db_user, 1)
+                if daily_discount > 0:
+                    daily_price = _apply_promo_discount(daily_price, group_pct, offer_pct)
+                    discount_icon = '🔥'
+            price_text = f'🔄 {format_price_kopeks(daily_price, compact=True)}/день{discount_icon}'
         else:
             # Для периодных тарифов показываем минимальную цену
             prices = tariff.period_prices or {}
@@ -394,21 +399,42 @@ def _calculate_custom_tariff_price(
     return period_price, traffic_price, total_price
 
 
-def format_custom_tariff_preview(
+async def format_custom_tariff_preview(
     tariff: Tariff,
     days: int,
     traffic_gb: int,
     user_balance: int,
+    db_user: User | None = None,
     discount_percent: int = 0,
     group_pct: int = 0,
     offer_pct: int = 0,
 ) -> str:
-    """Форматирует предпросмотр покупки с кастомными параметрами."""
-    period_price, traffic_price, total_price = _calculate_custom_tariff_price(tariff, days, traffic_gb)
+    """Форматирует предпросмотр покупки с кастомными параметрами.
 
-    # Применяем скидку
-    if discount_percent > 0:
-        total_price = _apply_promo_discount(total_price, group_pct, offer_pct)
+    Uses PricingEngine when db_user is provided for accurate per-category discounts
+    (period, traffic addon). Falls back to manual calculation otherwise.
+    """
+    if db_user is not None:
+        # Use PricingEngine — single source of truth for all discounts
+        from app.services.pricing_engine import pricing_engine
+
+        result = await pricing_engine.calculate_tariff_purchase_price(
+            tariff,
+            days,
+            device_limit=tariff.device_limit,
+            custom_traffic_gb=traffic_gb if tariff.can_purchase_custom_traffic() else None,
+            user=db_user,
+        )
+        period_price = result.base_price
+        traffic_price = result.traffic_price
+        total_price = result.final_total
+        has_discount = result.promo_group_discount > 0 or result.promo_offer_discount > 0
+    else:
+        # Fallback: raw prices without discounts
+        period_price, traffic_price, total_price = _calculate_custom_tariff_price(tariff, days, traffic_gb)
+        has_discount = discount_percent > 0
+        if has_discount:
+            total_price = _apply_promo_discount(total_price, group_pct, offer_pct)
 
     traffic_display = f'{traffic_gb} ГБ' if traffic_gb > 0 else format_traffic(tariff.traffic_limit_gb)
 
@@ -433,7 +459,7 @@ def format_custom_tariff_preview(
 
     text += f'📱 Устройств: {tariff.device_limit}\n'
 
-    if discount_percent > 0:
+    if has_discount:
         text += f'\n🎁 <b>Скидка: {discount_percent}%</b>\n'
 
     text += f"""
@@ -477,7 +503,9 @@ async def show_tariffs_list(
         return
 
     # Проверяем есть ли у пользователя скидки по периодам
-    promo_group = getattr(db_user, 'promo_group', None)
+    promo_group = db_user.get_primary_promo_group() if hasattr(db_user, 'get_primary_promo_group') else None
+    if promo_group is None:
+        promo_group = getattr(db_user, 'promo_group', None)
     has_period_discounts = False
     if promo_group:
         period_discounts = getattr(promo_group, 'period_discounts', None)
@@ -514,7 +542,12 @@ async def select_tariff(
 
     if is_daily:
         # Для суточного тарифа показываем подтверждение без выбора периода
-        daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+        raw_daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+        group_pct, offer_pct, daily_discount = _get_user_period_discount(db_user, 1)
+        daily_price = (
+            _apply_promo_discount(raw_daily_price, group_pct, offer_pct) if daily_discount > 0 else raw_daily_price
+        )
+        discount_text = f'\n💎 Скидка: {daily_discount}%' if daily_discount > 0 else ''
         user_balance = db_user.balance_kopeks or 0
         traffic = format_traffic(tariff.traffic_limit_gb)
 
@@ -525,7 +558,8 @@ async def select_tariff(
                 f'📊 Трафик: {traffic}\n'
                 f'📱 Устройств: {tariff.device_limit}\n'
                 f'🔄 Тип: <b>Суточный</b>\n\n'
-                f'💰 <b>Цена: {format_price_kopeks(daily_price)}/день</b>\n\n'
+                f'💰 <b>Цена: {format_price_kopeks(daily_price)}/день</b>'
+                f'{discount_text}\n\n'
                 f'💳 Ваш баланс: {format_price_kopeks(user_balance)}\n\n'
                 f'ℹ️ Средства будут списываться автоматически раз в сутки.\n'
                 f'Вы можете приостановить подписку в любой момент.',
@@ -557,7 +591,8 @@ async def select_tariff(
                 f'❌ <b>Недостаточно средств</b>\n\n'
                 f'📦 Тариф: <b>{tariff.name}</b>\n'
                 f'🔄 Тип: Суточный\n'
-                f'💰 Цена: {format_price_kopeks(daily_price)}/день\n\n'
+                f'💰 Цена: {format_price_kopeks(daily_price)}/день'
+                f'{discount_text}\n\n'
                 f'💳 Ваш баланс: {format_price_kopeks(user_balance)}\n'
                 f'⚠️ Не хватает: <b>{format_price_kopeks(missing)}</b>\n\n'
                 f'🛒 <i>Корзина сохранена! После пополнения баланса подписка будет оформлена автоматически.</i>',
@@ -588,14 +623,13 @@ async def select_tariff(
                 period_offer_pct=offer_pct,
             )
 
-            preview_text = format_custom_tariff_preview(
+            preview_text = await format_custom_tariff_preview(
                 tariff=tariff,
                 days=initial_days,
                 traffic_gb=initial_traffic,
                 user_balance=user_balance,
+                db_user=db_user,
                 discount_percent=discount_percent,
-                group_pct=group_pct,
-                offer_pct=offer_pct,
             )
 
             await callback.message.edit_text(
@@ -672,14 +706,13 @@ async def handle_custom_days_change(
 
     user_balance = db_user.balance_kopeks or 0
 
-    preview_text = format_custom_tariff_preview(
+    preview_text = await format_custom_tariff_preview(
         tariff=tariff,
         days=new_days,
         traffic_gb=current_traffic,
         user_balance=user_balance,
+        db_user=db_user,
         discount_percent=discount_percent,
-        group_pct=group_pct,
-        offer_pct=offer_pct,
     )
 
     await callback.message.edit_text(
@@ -722,8 +755,6 @@ async def handle_custom_traffic_change(
     current_days = state_data.get('custom_days', tariff.min_days)
     current_traffic = state_data.get('custom_traffic_gb', tariff.min_traffic_gb)
     discount_percent = state_data.get('period_discount_percent', 0)
-    group_pct = state_data.get('period_group_pct', 0)
-    offer_pct = state_data.get('period_offer_pct', 0)
 
     # Применяем изменение
     new_traffic = current_traffic + delta
@@ -733,14 +764,13 @@ async def handle_custom_traffic_change(
 
     user_balance = db_user.balance_kopeks or 0
 
-    preview_text = format_custom_tariff_preview(
+    preview_text = await format_custom_tariff_preview(
         tariff=tariff,
         days=current_days,
         traffic_gb=new_traffic,
         user_balance=user_balance,
+        db_user=db_user,
         discount_percent=discount_percent,
-        group_pct=group_pct,
-        offer_pct=offer_pct,
     )
 
     await callback.message.edit_text(
@@ -777,28 +807,33 @@ async def handle_custom_confirm(
         await callback.answer('Тариф недоступен', show_alert=True)
         return
 
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
     state_data = await state.get_data()
     custom_days = state_data.get('custom_days', tariff.min_days)
     custom_traffic = state_data.get('custom_traffic_gb', tariff.min_traffic_gb)
-    discount_percent = state_data.get('period_discount_percent', 0)
-    group_pct = state_data.get('period_group_pct', 0)
-    offer_pct = state_data.get('period_offer_pct', 0)
 
-    # Рассчитываем цену (используем общую функцию)
-    period_price, traffic_price, total_price = _calculate_custom_tariff_price(tariff, custom_days, custom_traffic)
+    # Calculate price via PricingEngine (single source of truth for all discounts)
+    from app.services.pricing_engine import pricing_engine
+
+    result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        custom_days,
+        device_limit=tariff.device_limit,
+        custom_traffic_gb=custom_traffic if tariff.can_purchase_custom_traffic() else None,
+        user=db_user,
+    )
+    total_price = result.final_total
 
     # Проверяем, что цена за период валидна
-    if period_price == 0 and not tariff.can_purchase_custom_days():
-        # Период не найден в period_prices - ошибка
+    if result.base_price == 0 and not tariff.can_purchase_custom_days():
         await callback.answer('Выбранный период недоступен для этого тарифа', show_alert=True)
         return
 
-    # Применяем скидку к цене периода (не к трафику)
-    if discount_percent > 0:
-        period_price = _apply_promo_discount(period_price, group_pct, offer_pct)
-        total_price = period_price + traffic_price
-
-    # Проверяем баланс
+    # Проверяем баланс (user already locked, balance is fresh)
     user_balance = db_user.balance_kopeks or 0
     if user_balance < total_price:
         await callback.answer('Недостаточно средств на балансе', show_alert=True)
@@ -807,7 +842,7 @@ async def handle_custom_confirm(
     texts = get_texts(db_user.language)
 
     # Save promo offer state before deduction (for restore on failure)
-    consume_promo = get_user_active_promo_discount_percent(db_user) > 0
+    consume_promo = result.promo_offer_discount > 0
     saved_promo_percent = int(getattr(db_user, 'promo_offer_discount_percent', 0) or 0) if consume_promo else 0
     saved_promo_source = getattr(db_user, 'promo_offer_discount_source', None) if consume_promo else None
     saved_promo_expires = getattr(db_user, 'promo_offer_discount_expires_at', None) if consume_promo else None
@@ -1014,14 +1049,13 @@ async def select_tariff_period_with_traffic(
         period_offer_pct=offer_pct,
     )
 
-    preview_text = format_custom_tariff_preview(
+    preview_text = await format_custom_tariff_preview(
         tariff=tariff,
         days=period,
         traffic_gb=initial_traffic,
         user_balance=user_balance,
+        db_user=db_user,
         discount_percent=discount_percent,
-        group_pct=group_pct,
-        offer_pct=offer_pct,
     )
 
     await callback.message.edit_text(
@@ -1152,34 +1186,28 @@ async def confirm_tariff_purchase(
         await callback.answer('Тариф недоступен', show_alert=True)
         return
 
-    # Получаем цену
-    prices = tariff.period_prices or {}
-    base_price = prices.get(str(period), 0)
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # Calculate price via PricingEngine (single source of truth)
+    from app.services.pricing_engine import pricing_engine
 
-    # Add extra device cost if user has more devices than tariff's included limit
     existing_sub = await get_subscription_by_user_id(db, db_user.id)
-    device_price_per_unit = (
-        tariff.device_price_kopeks if tariff.device_price_kopeks is not None else settings.PRICE_PER_DEVICE
-    )
-    extra_devices = 0
+    device_limit = None
     if existing_sub and existing_sub.tariff_id == tariff.id:
-        extra_devices = max(0, (existing_sub.device_limit or 0) - (tariff.device_limit or 0))
-    devices_price = extra_devices * device_price_per_unit
+        device_limit = existing_sub.device_limit
 
-    # Apply discounts sequentially (matching PricingEngine): group first, then offer
-    subtotal = base_price + devices_price
-    promo_group = db_user.get_primary_promo_group()
-    group_discount_pct = promo_group.get_discount_percent('period', period) if promo_group else 0
-    if group_discount_pct > 0:
-        subtotal = subtotal - subtotal * group_discount_pct // 100
+    result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        period,
+        device_limit=device_limit,
+        user=db_user,
+    )
+    final_price = result.final_total
 
-    offer_discount_pct = get_user_active_promo_discount_percent(db_user)
-    if offer_discount_pct > 0:
-        subtotal = subtotal - subtotal * offer_discount_pct // 100
-
-    final_price = max(0, subtotal)
-
-    # Проверяем баланс
+    # Проверяем баланс (user already locked, balance is fresh)
     user_balance = db_user.balance_kopeks or 0
     if user_balance < final_price:
         await callback.answer('Недостаточно средств на балансе', show_alert=True)
@@ -1188,7 +1216,7 @@ async def confirm_tariff_purchase(
     texts = get_texts(db_user.language)
 
     # Списываем баланс
-    consume_promo = get_user_active_promo_discount_percent(db_user) > 0
+    consume_promo = result.promo_offer_discount > 0
     # Save promo offer state before deduction (for restore on failure)
     saved_promo_percent = int(getattr(db_user, 'promo_offer_discount_percent', 0) or 0) if consume_promo else 0
     saved_promo_source = getattr(db_user, 'promo_offer_discount_source', None) if consume_promo else None
@@ -1382,9 +1410,26 @@ async def confirm_daily_tariff_purchase(
         await callback.answer('Некорректная цена тарифа', show_alert=True)
         return
 
-    # Проверяем баланс
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # Apply group + promo-offer discounts via PricingEngine (single source of truth)
+    from app.services.pricing_engine import pricing_engine
+
+    pricing_result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        period_days=1,
+        device_limit=tariff.device_limit,
+        user=db_user,
+    )
+    final_daily_price = pricing_result.final_total
+    consume_promo = pricing_result.breakdown.get('offer_discount_pct', 0) > 0
+
+    # Проверяем баланс (user already locked, balance is fresh)
     user_balance = db_user.balance_kopeks or 0
-    if user_balance < daily_price:
+    if user_balance < final_daily_price:
         await callback.answer('Недостаточно средств на балансе', show_alert=True)
         return
 
@@ -1395,8 +1440,9 @@ async def confirm_daily_tariff_purchase(
         success = await subtract_user_balance(
             db,
             db_user,
-            daily_price,
+            final_daily_price,
             f'Покупка суточного тарифа {tariff.name} (первый день)',
+            consume_promo_offer=consume_promo,
             mark_as_paid_subscription=True,
         )
         if not success:
@@ -1485,7 +1531,7 @@ async def confirm_daily_tariff_purchase(
             await add_user_balance(
                 db,
                 db_user,
-                daily_price,
+                final_daily_price,
                 'Возврат: ошибка покупки суточного тарифа',
                 create_transaction=True,
                 transaction_type=TransactionType.REFUND,
@@ -1494,7 +1540,7 @@ async def confirm_daily_tariff_purchase(
             logger.critical(
                 'CRITICAL: не удалось вернуть средства после ошибки покупки суточного тарифа',
                 user_id=db_user.id,
-                price_kopeks=daily_price,
+                price_kopeks=final_daily_price,
                 refund_error=refund_error,
             )
         await callback.answer('Произошла ошибка при оформлении подписки', show_alert=True)
@@ -1518,7 +1564,7 @@ async def confirm_daily_tariff_purchase(
         db,
         user_id=db_user.id,
         type=TransactionType.SUBSCRIPTION_PAYMENT,
-        amount_kopeks=daily_price,
+        amount_kopeks=final_daily_price,
         description=f'Покупка суточного тарифа {tariff.name} (первый день)',
     )
 
@@ -1532,7 +1578,7 @@ async def confirm_daily_tariff_purchase(
             None,
             1,  # 1 день
             was_trial_conversion=False,
-            amount_kopeks=daily_price,
+            amount_kopeks=final_daily_price,
             purchase_type='renewal' if existing_subscription else 'first_purchase',
         )
     except Exception as e:
@@ -1555,7 +1601,7 @@ async def confirm_daily_tariff_purchase(
         f'📊 Трафик: {traffic}\n'
         f'📱 Устройств: {tariff.device_limit}\n'
         f'🔄 Тип: Суточный\n'
-        f'💰 Списано: {format_price_kopeks(daily_price)}\n\n'
+        f'💰 Списано: {format_price_kopeks(final_daily_price)}\n\n'
         f'ℹ️ Следующее списание через 24 часа.\n'
         f'Перейдите в раздел «Подписка» для подключения.',
         reply_markup=InlineKeyboardMarkup(
@@ -1591,26 +1637,39 @@ def get_tariff_extend_keyboard(
     subscription_device_limit: int | None = None,
 ) -> InlineKeyboardMarkup:
     """Создает клавиатуру выбора периода для продления по тарифу с учетом скидок по периодам."""
+    from app.services.pricing_engine import PricingEngine
+
     texts = get_texts(language)
     buttons = []
 
+    promo_group = PricingEngine.resolve_promo_group(db_user) if db_user else None
+
     prices = tariff.period_prices or {}
     for period_str in sorted(prices.keys(), key=int):
         period = int(period_str)
-        price = prices[period_str]
+        base_price = prices[period_str]
 
-        # Добавляем стоимость дополнительных устройств
+        # Стоимость дополнительных устройств
+        devices_cost = 0
         if subscription_device_limit is not None:
-            price += _calc_extra_devices_cost(tariff, subscription_device_limit, period)
+            devices_cost = _calc_extra_devices_cost(tariff, subscription_device_limit, period)
 
-        # Получаем скидку для конкретного периода
-        group_pct, offer_pct, discount_percent = 0, 0, 0
-        if db_user:
-            group_pct, offer_pct, discount_percent = _get_user_period_discount(db_user, period)
+        # Per-category group discounts (period + devices separately, like PricingEngine)
+        period_pct = promo_group.get_discount_percent('period', period) if promo_group else 0
+        devices_pct = promo_group.get_discount_percent('devices', period) if promo_group else 0
+        offer_pct = get_user_active_promo_discount_percent(db_user) if db_user else 0
 
-        if discount_percent > 0:
-            price = _apply_promo_discount(price, group_pct, offer_pct)
-            price_text = f'{format_price_kopeks(price)} 🔥−{discount_percent}%'
+        discounted_base = PricingEngine.apply_discount(base_price, period_pct)
+        discounted_devices = PricingEngine.apply_discount(devices_cost, devices_pct)
+        subtotal = discounted_base + discounted_devices
+        price = PricingEngine.apply_discount(subtotal, offer_pct)
+
+        # Combined display discount
+        total_original = base_price + devices_cost
+        has_discount = price < total_original and total_original > 0
+        if has_discount:
+            combined_pct = round((1 - price / total_original) * 100)
+            price_text = f'{format_price_kopeks(price)} 🔥−{combined_pct}%'
         else:
             price_text = format_price_kopeks(price)
 
@@ -1662,7 +1721,9 @@ async def show_tariff_extend(
     traffic = format_traffic(tariff.traffic_limit_gb)
 
     # Проверяем есть ли у пользователя скидки по периодам
-    promo_group = getattr(db_user, 'promo_group', None)
+    promo_group = db_user.get_primary_promo_group() if hasattr(db_user, 'get_primary_promo_group') else None
+    if promo_group is None:
+        promo_group = getattr(db_user, 'promo_group', None)
     has_period_discounts = False
     if promo_group:
         period_discounts = getattr(promo_group, 'period_discounts', None)
@@ -1716,14 +1777,21 @@ async def select_tariff_extend_period(
     subscription = await get_subscription_by_user_id(db, db_user.id)
     actual_device_limit = (subscription.device_limit if subscription else None) or tariff.device_limit
 
-    # Получаем скидку для выбранного периода
-    group_pct, offer_pct, discount_percent = _get_user_period_discount(db_user, period)
+    # Calculate price via PricingEngine (per-category discounts: period + devices)
+    from app.services.pricing_engine import pricing_engine
 
-    # Получаем цену (тариф + дополнительные устройства)
-    prices = tariff.period_prices or {}
-    base_price = prices.get(str(period), 0)
-    base_price += _calc_extra_devices_cost(tariff, actual_device_limit, period)
-    final_price = _apply_promo_discount(base_price, group_pct, offer_pct)
+    result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        period,
+        device_limit=actual_device_limit,
+        user=db_user,
+    )
+    final_price = result.final_total
+    original_price = result.original_total
+    total_discount = result.promo_group_discount + result.promo_offer_discount
+    discount_percent = (
+        round((1 - final_price / original_price) * 100) if original_price > 0 and total_discount > 0 else 0
+    )
 
     # Проверяем баланс
     user_balance = db_user.balance_kopeks or 0
@@ -1733,7 +1801,7 @@ async def select_tariff_extend_period(
     if user_balance >= final_price:
         discount_text = ''
         if discount_percent > 0:
-            discount_text = f'\n🎁 Скидка: {discount_percent}% (-{format_price_kopeks(base_price - final_price)})'
+            discount_text = f'\n🎁 Скидка: {discount_percent}% (-{format_price_kopeks(total_discount)})'
 
         await callback.message.edit_text(
             f'✅ <b>Подтверждение продления</b>\n\n'
@@ -1821,15 +1889,21 @@ async def confirm_tariff_extend(
 
     actual_device_limit = subscription.device_limit or tariff.device_limit
 
-    data = await state.get_data()
-    group_pct = data.get('extend_group_pct', 0)
-    offer_pct = data.get('extend_offer_pct', 0)
+    from app.database.crud.user import lock_user_for_pricing
 
-    # Получаем цену (тариф + дополнительные устройства)
-    prices = tariff.period_prices or {}
-    base_price = prices.get(str(period), 0)
-    base_price += _calc_extra_devices_cost(tariff, actual_device_limit, period)
-    final_price = _apply_promo_discount(base_price, group_pct, offer_pct)
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # Calculate price via PricingEngine (handles per-category discounts: period + devices)
+    from app.services.pricing_engine import pricing_engine
+
+    result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        period,
+        device_limit=actual_device_limit,
+        user=db_user,
+    )
+    final_price = result.final_total
+    consume_promo = result.promo_offer_discount > 0
 
     # Проверяем баланс
     user_balance = db_user.balance_kopeks or 0
@@ -1846,7 +1920,7 @@ async def confirm_tariff_extend(
             db_user,
             final_price,
             f'Продление тарифа {tariff.name} на {period} дней',
-            consume_promo_offer=get_user_active_promo_discount_percent(db_user) > 0,
+            consume_promo_offer=consume_promo,
             mark_as_paid_subscription=True,
         )
         if not success:
@@ -1966,9 +2040,14 @@ def format_tariff_switch_list_text(
         discount_icon = ''
 
         if is_daily:
-            # Для суточных тарифов показываем цену за день
+            # Для суточных тарифов показываем цену за день с учётом скидки промогруппы
             daily_price = getattr(tariff, 'daily_price_kopeks', 0)
-            price_text = f'🔄 {format_price_kopeks(daily_price, compact=True)}/день'
+            if db_user:
+                group_pct, offer_pct, daily_discount = _get_user_period_discount(db_user, 1)
+                if daily_discount > 0:
+                    daily_price = _apply_promo_discount(daily_price, group_pct, offer_pct)
+                    discount_icon = '🔥'
+            price_text = f'🔄 {format_price_kopeks(daily_price, compact=True)}/день{discount_icon}'
         else:
             prices = tariff.period_prices or {}
             if prices:
@@ -2124,7 +2203,9 @@ async def show_tariff_switch_list(
             current_tariff_name = current_tariff.name
 
     # Проверяем есть ли у пользователя скидки по периодам
-    promo_group = getattr(db_user, 'promo_group', None)
+    promo_group = db_user.get_primary_promo_group() if hasattr(db_user, 'get_primary_promo_group') else None
+    if promo_group is None:
+        promo_group = getattr(db_user, 'promo_group', None)
     has_period_discounts = False
     if promo_group:
         period_discounts = getattr(promo_group, 'period_discounts', None)
@@ -2170,7 +2251,12 @@ async def select_tariff_switch(
 
     if is_daily:
         # Для суточного тарифа показываем подтверждение без выбора периода
-        daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+        raw_daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+        group_pct, offer_pct, daily_discount = _get_user_period_discount(db_user, 1)
+        daily_price = (
+            _apply_promo_discount(raw_daily_price, group_pct, offer_pct) if daily_discount > 0 else raw_daily_price
+        )
+        discount_text = f'\n💎 Скидка: {daily_discount}%' if daily_discount > 0 else ''
         user_balance = db_user.balance_kopeks or 0
 
         # Проверяем текущую подписку на оставшиеся дни
@@ -2189,7 +2275,8 @@ async def select_tariff_switch(
                 f'📊 Трафик: {traffic}\n'
                 f'📱 Устройств: {tariff.device_limit}\n'
                 f'🔄 Тип: <b>Суточный</b>\n\n'
-                f'💰 <b>Цена: {format_price_kopeks(daily_price)}/день</b>\n\n'
+                f'💰 <b>Цена: {format_price_kopeks(daily_price)}/день</b>'
+                f'{discount_text}\n\n'
                 f'💳 Ваш баланс: {format_price_kopeks(user_balance)}'
                 f'{days_warning}\n\n'
                 f'ℹ️ Средства будут списываться автоматически раз в сутки.\n'
@@ -2212,7 +2299,8 @@ async def select_tariff_switch(
                 f'❌ <b>Недостаточно средств</b>\n\n'
                 f'📦 Тариф: <b>{tariff.name}</b>\n'
                 f'🔄 Тип: Суточный\n'
-                f'💰 Цена: {format_price_kopeks(daily_price)}/день\n\n'
+                f'💰 Цена: {format_price_kopeks(daily_price)}/день'
+                f'{discount_text}\n\n'
                 f'💳 Ваш баланс: {format_price_kopeks(user_balance)}\n'
                 f'⚠️ Не хватает: <b>{format_price_kopeks(missing)}</b>'
                 f'{days_warning}',
@@ -2269,13 +2357,21 @@ async def select_tariff_switch_period(
     data = await state.get_data()
     current_tariff_id = data.get('current_tariff_id')
 
-    # Получаем скидку для выбранного периода
-    group_pct, offer_pct, discount_percent = _get_user_period_discount(db_user, period)
+    # Calculate price via PricingEngine (per-category discounts: period + devices for new tariff)
+    from app.services.pricing_engine import pricing_engine
 
-    # Получаем цену
-    prices = tariff.period_prices or {}
-    base_price = prices.get(str(period), 0)
-    final_price = _apply_promo_discount(base_price, group_pct, offer_pct)
+    result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        period,
+        device_limit=tariff.device_limit or 0,
+        user=db_user,
+    )
+    final_price = result.final_total
+    original_price = result.original_total
+    total_discount = result.promo_group_discount + result.promo_offer_discount
+    discount_percent = (
+        round((1 - final_price / original_price) * 100) if original_price > 0 and total_discount > 0 else 0
+    )
 
     # Проверяем баланс
     user_balance = db_user.balance_kopeks or 0
@@ -2300,7 +2396,7 @@ async def select_tariff_switch_period(
     if user_balance >= final_price:
         discount_text = ''
         if discount_percent > 0:
-            discount_text = f'\n🎁 Скидка: {discount_percent}% (-{format_price_kopeks(base_price - final_price)})'
+            discount_text = f'\n🎁 Скидка: {discount_percent}% (-{format_price_kopeks(total_discount)})'
 
         await callback.message.edit_text(
             f'✅ <b>Подтверждение переключения тарифа</b>\n\n'
@@ -2354,13 +2450,30 @@ async def confirm_tariff_switch(
         await callback.answer('Тариф недоступен', show_alert=True)
         return
 
-    # Получаем скидку для выбранного периода
-    group_pct, offer_pct, discount_percent = _get_user_period_discount(db_user, period)
+    from app.database.crud.user import lock_user_for_pricing
 
-    # Получаем цену
-    prices = tariff.period_prices or {}
-    base_price = prices.get(str(period), 0)
-    final_price = _apply_promo_discount(base_price, group_pct, offer_pct)
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # Проверяем наличие подписки (need device_limit for pricing)
+    subscription = await get_subscription_by_user_id(db, db_user.id)
+    if not subscription:
+        await callback.answer('У вас нет активной подписки', show_alert=True)
+        return
+
+    # Calculate price via PricingEngine (handles per-category discounts + extra devices)
+    from app.services.pricing_engine import pricing_engine
+
+    effective_device_limit = (
+        subscription.device_limit if subscription.tariff_id == tariff.id else (tariff.device_limit or 0)
+    )
+    result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        period,
+        device_limit=effective_device_limit,
+        user=db_user,
+    )
+    final_price = result.final_total
+    consume_promo = result.promo_offer_discount > 0
 
     # Проверяем баланс
     user_balance = db_user.balance_kopeks or 0
@@ -2368,12 +2481,6 @@ async def confirm_tariff_switch(
         await callback.answer('Недостаточно средств на балансе', show_alert=True)
         return
 
-    # Проверяем наличие подписки
-    subscription = await get_subscription_by_user_id(db, db_user.id)
-    if not subscription:
-        await callback.answer('У вас нет активной подписки', show_alert=True)
-        return
-
     texts = get_texts(db_user.language)
 
     try:
@@ -2383,7 +2490,7 @@ async def confirm_tariff_switch(
             db_user,
             final_price,
             f'Смена тарифа на {tariff.name} ({period} дней)',
-            consume_promo_offer=get_user_active_promo_discount_percent(db_user) > 0,
+            consume_promo_offer=consume_promo,
             mark_as_paid_subscription=True,
         )
         if not success:
@@ -2536,9 +2643,26 @@ async def confirm_daily_tariff_switch(
         await callback.answer('Некорректная цена тарифа', show_alert=True)
         return
 
-    # Проверяем баланс
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # Apply group + promo-offer discounts via PricingEngine (single source of truth)
+    from app.services.pricing_engine import pricing_engine
+
+    pricing_result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        period_days=1,
+        device_limit=tariff.device_limit,
+        user=db_user,
+    )
+    final_daily_price = pricing_result.final_total
+    consume_promo = pricing_result.breakdown.get('offer_discount_pct', 0) > 0
+
+    # Проверяем баланс (user already locked, balance is fresh)
     user_balance = db_user.balance_kopeks or 0
-    if user_balance < daily_price:
+    if user_balance < final_daily_price:
         await callback.answer('Недостаточно средств на балансе', show_alert=True)
         return
 
@@ -2555,8 +2679,9 @@ async def confirm_daily_tariff_switch(
         success = await subtract_user_balance(
             db,
             db_user,
-            daily_price,
+            final_daily_price,
             f'Смена на суточный тариф {tariff.name} (первый день)',
+            consume_promo_offer=consume_promo,
             mark_as_paid_subscription=True,
         )
         if not success:
@@ -2639,7 +2764,7 @@ async def confirm_daily_tariff_switch(
             db,
             user_id=db_user.id,
             type=TransactionType.SUBSCRIPTION_PAYMENT,
-            amount_kopeks=daily_price,
+            amount_kopeks=final_daily_price,
             description=f'Смена на суточный тариф {tariff.name} (первый день)',
         )
 
@@ -2653,7 +2778,7 @@ async def confirm_daily_tariff_switch(
                 None,
                 1,  # 1 день
                 was_trial_conversion=False,
-                amount_kopeks=daily_price,
+                amount_kopeks=final_daily_price,
                 purchase_type='tariff_switch',
             )
         except Exception as e:
@@ -2669,7 +2794,7 @@ async def confirm_daily_tariff_switch(
             f'📊 Трафик: {traffic}\n'
             f'📱 Устройств: {tariff.device_limit}\n'
             f'🔄 Тип: Суточный\n'
-            f'💰 Списано: {format_price_kopeks(daily_price)}\n\n'
+            f'💰 Списано: {format_price_kopeks(final_daily_price)}\n\n'
             f'ℹ️ Следующее списание через 24 часа.',
             reply_markup=InlineKeyboardMarkup(
                 inline_keyboard=[
@@ -2683,65 +2808,53 @@ async def confirm_daily_tariff_switch(
 
     except Exception as e:
         logger.error('Ошибка при смене на суточный тариф', error=e, exc_info=True)
+        await db.rollback()
+        # Compensating refund: balance was already committed by subtract_user_balance
+        try:
+            from app.database.crud.user import add_user_balance
+
+            await add_user_balance(
+                db,
+                db_user,
+                final_daily_price,
+                'Возврат: ошибка смены на суточный тариф',
+                create_transaction=True,
+                transaction_type=TransactionType.REFUND,
+            )
+        except Exception as refund_error:
+            logger.critical(
+                'CRITICAL: не удалось вернуть средства после ошибки смены на суточный тариф',
+                user_id=db_user.id,
+                price_kopeks=final_daily_price,
+                refund_error=refund_error,
+            )
         await callback.answer('Произошла ошибка при смене тарифа', show_alert=True)
 
 
 # ==================== Мгновенное переключение тарифов (без выбора периода) ====================
 
 
-def _get_tariff_monthly_price(tariff: Tariff) -> int:
-    """Получает месячную цену тарифа (30 дней) с fallback на пропорциональный расчёт."""
-    price = tariff.get_price_for_period(30)
-    if price is not None:
-        return price
-
-    # Fallback: пропорционально пересчитываем из первого доступного периода
-    periods = tariff.get_available_periods()
-    if periods:
-        first_period = periods[0]
-        first_price = tariff.get_price_for_period(first_period)
-        if first_price:
-            return int(first_price * 30 / first_period)
-
-    return 0
-
-
 def _calculate_instant_switch_cost(
     current_tariff: Tariff,
     new_tariff: Tariff,
     remaining_days: int,
     db_user: User | None = None,
 ) -> tuple[int, bool]:
-    """
-    Рассчитывает стоимость мгновенного переключения тарифа.
-
-    Если новый тариф дороже - доплата пропорционально оставшимся дням.
-    Если дешевле или равен - бесплатно.
-
-    Формула: (new_monthly - current_monthly) * remaining_days / 30
-    Скидка применяется к обоим тарифам одинаково.
+    """Рассчитывает стоимость мгновенного переключения тарифа.
 
+    Делегирует расчёт в PricingEngine.calculate_tariff_switch_cost().
     Returns:
         (upgrade_cost_kopeks, is_upgrade)
     """
-    current_monthly = _get_tariff_monthly_price(current_tariff)
-    new_monthly = _get_tariff_monthly_price(new_tariff)
+    from app.services.pricing_engine import pricing_engine
 
-    group_pct, offer_pct, discount_percent = 0, 0, 0
-    if db_user:
-        group_pct, offer_pct, discount_percent = _get_user_period_discount(db_user, 30)
-
-    if discount_percent > 0:
-        current_monthly = _apply_promo_discount(current_monthly, group_pct, offer_pct)
-        new_monthly = _apply_promo_discount(new_monthly, group_pct, offer_pct)
-
-    price_diff = new_monthly - current_monthly
-
-    if price_diff <= 0:
-        return 0, False
-
-    upgrade_cost = int(price_diff * remaining_days / 30)
-    return upgrade_cost, True
+    result = pricing_engine.calculate_tariff_switch_cost(
+        current_tariff,
+        new_tariff,
+        remaining_days,
+        user=db_user,
+    )
+    return result.upgrade_cost, result.is_upgrade
 
 
 def format_instant_switch_list_text(
@@ -2984,7 +3097,15 @@ async def preview_instant_switch(
 
     # Для суточного тарифа особая логика показа
     if is_new_daily:
-        daily_price = getattr(new_tariff, 'daily_price_kopeks', 0)
+        raw_daily_price = getattr(new_tariff, 'daily_price_kopeks', 0)
+        # Применяем групповую скидку + promo-offer для отображения
+        daily_group_pct, daily_offer_pct, daily_discount = _get_user_period_discount(db_user, 1)
+        daily_price = (
+            _apply_promo_discount(raw_daily_price, daily_group_pct, daily_offer_pct)
+            if daily_discount > 0
+            else raw_daily_price
+        )
+        discount_text = f'\n💎 Скидка: {daily_discount}%' if daily_discount > 0 else ''
         user_balance = db_user.balance_kopeks or 0
 
         if user_balance >= daily_price:
@@ -2997,7 +3118,8 @@ async def preview_instant_switch(
                 f'   • Трафик: {traffic}\n'
                 f'   • Устройств: {new_tariff.device_limit}\n'
                 f'   • Тип: 🔄 Суточный\n\n'
-                f'💰 <b>Цена: {format_price_kopeks(daily_price)}/день</b>\n\n'
+                f'💰 <b>Цена: {format_price_kopeks(daily_price)}/день</b>'
+                f'{discount_text}\n\n'
                 f'💳 Ваш баланс: {format_price_kopeks(user_balance)}'
                 f'{daily_warning}\n\n'
                 f'ℹ️ Средства будут списываться автоматически раз в сутки.',
@@ -3010,7 +3132,8 @@ async def preview_instant_switch(
                 f'❌ <b>Недостаточно средств</b>\n\n'
                 f'📦 Тариф: <b>{new_tariff.name}</b>\n'
                 f'🔄 Тип: Суточный\n'
-                f'💰 Цена: {format_price_kopeks(daily_price)}/день\n\n'
+                f'💰 Цена: {format_price_kopeks(daily_price)}/день'
+                f'{discount_text}\n\n'
                 f'💳 Ваш баланс: {format_price_kopeks(user_balance)}\n'
                 f'⚠️ Не хватает: <b>{format_price_kopeks(missing)}</b>'
                 f'{daily_warning}',
@@ -3099,19 +3222,37 @@ async def confirm_instant_switch(
         await callback.answer('Тариф недоступен', show_alert=True)
         return
 
-    # Получаем данные из состояния
-    data = await state.get_data()
-    upgrade_cost = data.get('upgrade_cost', 0)
-    is_upgrade = data.get('is_upgrade', False)
-    remaining_days = data.get('remaining_days', 0)
-
     # Проверяем подписку
     subscription = await get_subscription_by_user_id(db, db_user.id)
     if not subscription:
         await callback.answer('Подписка не найдена', show_alert=True)
         return
 
-    # Проверяем баланс если это upgrade
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
+    # Recompute upgrade_cost under lock (FSM-stored value may be stale)
+    current_tariff = await get_tariff_by_id(db, subscription.tariff_id) if subscription.tariff_id else None
+    if not current_tariff:
+        await callback.answer('Текущий тариф не найден', show_alert=True)
+        return
+    remaining_days = max(0, (subscription.end_date - datetime.now(UTC)).days) if subscription.end_date else 0
+
+    # Use full TariffSwitchResult to access offer_discount_pct for consume_promo_offer flag
+    from app.services.pricing_engine import pricing_engine
+
+    switch_result = pricing_engine.calculate_tariff_switch_cost(
+        current_tariff,
+        new_tariff,
+        remaining_days,
+        user=db_user,
+    )
+    upgrade_cost = switch_result.upgrade_cost
+    is_upgrade = switch_result.is_upgrade
+    consume_promo = switch_result.offer_discount_pct > 0
+
+    # Проверяем баланс если это upgrade (use locked user's fresh balance)
     user_balance = db_user.balance_kopeks or 0
     if is_upgrade and user_balance < upgrade_cost:
         await callback.answer('Недостаточно средств на балансе', show_alert=True)
@@ -3121,13 +3262,14 @@ async def confirm_instant_switch(
 
     try:
         # Списываем баланс если это upgrade
+        # upgrade_cost includes both group + offer discounts from PricingEngine
         if is_upgrade and upgrade_cost > 0:
             success = await subtract_user_balance(
                 db,
                 db_user,
                 upgrade_cost,
                 f'Переключение на тариф {new_tariff.name}',
-                consume_promo_offer=get_user_active_promo_discount_percent(db_user) > 0,
+                consume_promo_offer=consume_promo,
                 mark_as_paid_subscription=True,
             )
             if not success:
@@ -3176,7 +3318,15 @@ async def confirm_instant_switch(
 
         if is_new_daily:
             # Для суточного тарифа - сбрасываем на 1 день и настраиваем суточные параметры
-            daily_price = getattr(new_tariff, 'daily_price_kopeks', 0)
+            # Apply group + promo-offer discounts via PricingEngine (single source of truth)
+            daily_pricing = await pricing_engine.calculate_tariff_purchase_price(
+                new_tariff,
+                period_days=1,
+                device_limit=new_tariff.device_limit,
+                user=db_user,
+            )
+            daily_price = daily_pricing.final_total
+            consume_promo_for_daily = daily_pricing.breakdown.get('offer_discount_pct', 0) > 0
 
             # Списываем первый день если ещё не списано (upgrade_cost был 0)
             if upgrade_cost == 0 and daily_price > 0:
@@ -3186,6 +3336,7 @@ async def confirm_instant_switch(
                         db_user,
                         daily_price,
                         f'Переключение на суточный тариф {new_tariff.name} (первый день)',
+                        consume_promo_offer=consume_promo_for_daily,
                         mark_as_paid_subscription=True,
                     )
                     if not success:
@@ -3199,6 +3350,22 @@ async def confirm_instant_switch(
                         description=f'Переключение на суточный тариф {new_tariff.name} (первый день)',
                     )
 
+                    # Уведомление админу о списании за первый день суточного тарифа
+                    try:
+                        admin_notification_service = AdminNotificationService(callback.bot)
+                        await admin_notification_service.send_subscription_purchase_notification(
+                            db,
+                            db_user,
+                            subscription,
+                            None,
+                            1,
+                            was_trial_conversion=False,
+                            amount_kopeks=daily_price,
+                            purchase_type='tariff_switch',
+                        )
+                    except Exception as e:
+                        logger.error('Ошибка отправки уведомления админу', error=e)
+
             subscription.end_date = datetime.now(UTC) + timedelta(days=1)
             subscription.is_trial = False
             subscription.is_daily_paused = False
@@ -3266,7 +3433,6 @@ async def confirm_instant_switch(
 
         # Для суточного тарифа другое сообщение об успехе
         if is_new_daily:
-            daily_price = getattr(new_tariff, 'daily_price_kopeks', 0)
             await callback.message.edit_text(
                 f'🎉 <b>Тариф успешно изменён!</b>\n\n'
                 f'📦 Новый тариф: <b>{new_tariff.name}</b>\n'

app/handlers/subscription/traffic.py

@@ -19,18 +19,16 @@ from app.keyboards.inline import (
     get_reset_traffic_confirm_keyboard,
 )
 from app.localization.texts import get_texts
+from app.services.pricing_engine import PricingEngine
 from app.services.remnawave_service import RemnaWaveService
 from app.services.subscription_service import SubscriptionService
 from app.services.user_cart_service import user_cart_service
 from app.states import SubscriptionStates
 from app.utils.pricing_utils import (
-    apply_percentage_discount,
     calculate_prorated_price,
 )
 
 from .common import (
-    _apply_addon_discount,
-    _get_addon_discount_percent_for_user,
     _get_period_hint_from_subscription,
     get_confirm_switch_traffic_keyboard,
     get_traffic_switch_keyboard,
@@ -84,7 +82,7 @@ async def handle_add_traffic(callback: types.CallbackQuery, db_user: User, db: A
         packages = tariff.get_traffic_topup_packages()
 
         period_hint_days = _get_period_hint_from_subscription(subscription)
-        traffic_discount_percent = _get_addon_discount_percent_for_user(
+        traffic_discount_percent = PricingEngine.get_addon_discount_percent(
             db_user,
             'traffic',
             period_hint_days,
@@ -136,7 +134,7 @@ async def handle_add_traffic(callback: types.CallbackQuery, db_user: User, db: A
 
     current_traffic = subscription.traffic_limit_gb
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    traffic_discount_percent = _get_addon_discount_percent_for_user(
+    traffic_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'traffic',
         period_hint_days,
@@ -261,6 +259,10 @@ async def confirm_reset_traffic(callback: types.CallbackQuery, db_user: User, db
         await callback.answer('⚠️ В текущем режиме трафик фиксированный', show_alert=True)
         return
 
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+
     texts = get_texts(db_user.language)
     subscription = db_user.subscription
 
@@ -471,16 +473,18 @@ async def add_traffic(callback: types.CallbackQuery, db_user: User, db: AsyncSes
         await callback.answer('⚠️ Цена для этого пакета не настроена', show_alert=True)
         return
 
+    # Lock user BEFORE price computation to prevent TOCTOU on group discount
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
+    subscription = db_user.subscription
+
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    discount_result = _apply_addon_discount(
-        db_user,
-        'traffic',
+    discounted_per_month, discount_per_month, traffic_discount_pct = PricingEngine.calculate_traffic_discount(
         base_price,
+        db_user,
         period_hint_days,
     )
-
-    discounted_per_month = discount_result['discounted']
-    discount_per_month = discount_result['discount']
     charged_days = 30
 
     # На тарифах пакеты трафика покупаются на 1 месяц (30 дней),
@@ -510,7 +514,7 @@ async def add_traffic(callback: types.CallbackQuery, db_user: User, db: AsyncSes
             'traffic_gb': traffic_gb,
             'price_kopeks': price,
             'base_price_kopeks': discounted_per_month,
-            'discount_percent': discount_result['percent'],
+            'discount_percent': traffic_discount_pct,
             'source': 'bot',
             'description': f'Докупка {traffic_gb} ГБ трафика',
         }
@@ -619,7 +623,7 @@ async def add_traffic(callback: types.CallbackQuery, db_user: User, db: AsyncSes
         if price > 0:
             success_text += f'\n💰 Списано: {texts.format_price(price)}'
             if total_discount_value > 0:
-                success_text += f' (скидка {discount_result["percent"]}%: -{texts.format_price(total_discount_value)})'
+                success_text += f' (скидка {traffic_discount_pct}%: -{texts.format_price(total_discount_value)})'
 
         await callback.message.edit_text(success_text, reply_markup=get_back_keyboard(db_user.language))
 
@@ -668,7 +672,7 @@ async def handle_switch_traffic(callback: types.CallbackQuery, db_user: User, db
     base_traffic = current_traffic - purchased_traffic
 
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    traffic_discount_percent = _get_addon_discount_percent_for_user(
+    traffic_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'traffic',
         period_hint_days,
@@ -722,17 +726,17 @@ async def confirm_switch_traffic(callback: types.CallbackQuery, db_user: User, d
     now = datetime.now(UTC)
     days_remaining = max(1, (subscription.end_date - now).days)
     period_hint_days = days_remaining if days_remaining > 0 else None
-    traffic_discount_percent = _get_addon_discount_percent_for_user(
+    traffic_discount_percent = PricingEngine.get_addon_discount_percent(
         db_user,
         'traffic',
         period_hint_days,
     )
 
-    discounted_old_per_month, _ = apply_percentage_discount(
+    discounted_old_per_month = PricingEngine.apply_discount(
         old_price_per_month,
         traffic_discount_percent,
     )
-    discounted_new_per_month, _ = apply_percentage_discount(
+    discounted_new_per_month = PricingEngine.apply_discount(
         new_price_per_month,
         traffic_discount_percent,
     )
@@ -800,12 +804,35 @@ async def confirm_switch_traffic(callback: types.CallbackQuery, db_user: User, d
 async def execute_switch_traffic(callback: types.CallbackQuery, db_user: User, db: AsyncSession):
     callback_parts = callback.data.split('_')
     new_traffic_gb = int(callback_parts[3])
-    price_difference = int(callback_parts[4])
+
+    from app.database.crud.user import lock_user_for_pricing
+
+    db_user = await lock_user_for_pricing(db, db_user.id)
 
     texts = get_texts(db_user.language)
     subscription = db_user.subscription
     current_traffic = subscription.traffic_limit_gb
 
+    # Recompute price under lock (callback-baked value may be stale)
+    purchased_traffic = getattr(subscription, 'purchased_traffic_gb', 0) or 0
+    base_traffic = current_traffic - purchased_traffic
+    old_price_per_month = settings.get_traffic_price(base_traffic)
+    new_price_per_month = settings.get_traffic_price(new_traffic_gb)
+    days_remaining = max(1, (subscription.end_date - datetime.now(UTC)).days)
+    traffic_discount_percent = PricingEngine.get_addon_discount_percent(
+        db_user,
+        'traffic',
+        days_remaining,
+    )
+    discounted_old = PricingEngine.apply_discount(old_price_per_month, traffic_discount_percent)
+    discounted_new = PricingEngine.apply_discount(new_price_per_month, traffic_discount_percent)
+    price_diff_per_month = discounted_new - discounted_old
+    if price_diff_per_month > 0:
+        price_difference = int(price_diff_per_month * days_remaining / 30)
+        price_difference = max(100, price_difference)
+    else:
+        price_difference = 0
+
     try:
         if price_difference > 0:
             success = await subtract_user_balance(

app/services/daily_subscription_service.py

@@ -123,11 +123,25 @@ class DailySubscriptionService:
             logger.warning('Тариф не найден для подписки', subscription_id=subscription.id)
             return 'error'
 
-        daily_price = tariff.daily_price_kopeks
-        if daily_price <= 0:
+        raw_daily_price = tariff.daily_price_kopeks
+        if raw_daily_price <= 0:
             logger.warning('Некорректная суточная цена для тарифа', tariff_id=tariff.id)
             return 'error'
 
+        # Lock user row to prevent TOCTOU between discount read and balance charge
+        from app.database.crud.user import lock_user_for_pricing
+
+        user = await lock_user_for_pricing(db, user.id)
+
+        # Apply group discount to daily price (consistent with PricingEngine._calculate_switch_to_daily)
+        from app.services.pricing_engine import PricingEngine
+
+        promo_group = PricingEngine.resolve_promo_group(user)
+        daily_group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+        daily_price = (
+            PricingEngine.apply_discount(raw_daily_price, daily_group_pct) if daily_group_pct > 0 else raw_daily_price
+        )
+
         # Проверяем баланс
         if user.balance_kopeks < daily_price:
             # Недостаточно средств - приостанавливаем подписку

app/services/guest_purchase_service.py

@@ -118,7 +118,9 @@ async def validate_and_calculate(
             overrides = landing.discount_overrides or {}
             tariff_override = overrides.get(str(tariff_id))
             effective_discount = tariff_override if tariff_override is not None else landing.discount_percent
-            price_kopeks = max(1, price_kopeks - (price_kopeks * effective_discount // 100))
+            from app.services.pricing_engine import PricingEngine
+
+            price_kopeks = max(1, PricingEngine.apply_discount(price_kopeks, effective_discount))
 
     return tariff, price_kopeks
 
@@ -283,6 +285,13 @@ async def fulfill_purchase(
             )
             return purchase
 
+        squads = list(tariff.allowed_squads or [])
+        if not squads:
+            from app.database.crud.server_squad import get_all_server_squads
+
+            all_servers, _ = await get_all_server_squads(db, available_only=True)
+            squads = [s.squad_uuid for s in all_servers if s.squad_uuid]
+
         if existing_subscription is not None:
             # Expired/inactive subscription — replace it
             existing_subscription.tariff_id = tariff.id
@@ -292,7 +301,7 @@ async def fulfill_purchase(
                 duration_days=purchase.period_days,
                 traffic_limit_gb=tariff.traffic_limit_gb,
                 device_limit=tariff.device_limit,
-                connected_squads=tariff.allowed_squads or [],
+                connected_squads=squads,
                 is_trial=False,
                 update_server_counters=True,
             )
@@ -304,7 +313,7 @@ async def fulfill_purchase(
                 duration_days=purchase.period_days,
                 traffic_limit_gb=tariff.traffic_limit_gb,
                 device_limit=tariff.device_limit,
-                connected_squads=tariff.allowed_squads or [],
+                connected_squads=squads,
                 tariff_id=tariff.id,
                 update_server_counters=True,
             )
@@ -888,6 +897,13 @@ async def activate_purchase(db: AsyncSession, purchase_token: str, *, skip_notif
         existing_subscription = await get_subscription_by_user_id(db, user.id)
         subscription_service = SubscriptionService()
 
+        squads = list(tariff.allowed_squads or [])
+        if not squads:
+            from app.database.crud.server_squad import get_all_server_squads
+
+            all_servers, _ = await get_all_server_squads(db, available_only=True)
+            squads = [s.squad_uuid for s in all_servers if s.squad_uuid]
+
         if existing_subscription is not None:
             subscription = await replace_subscription(
                 db,
@@ -895,7 +911,7 @@ async def activate_purchase(db: AsyncSession, purchase_token: str, *, skip_notif
                 duration_days=purchase.period_days,
                 traffic_limit_gb=tariff.traffic_limit_gb,
                 device_limit=tariff.device_limit,
-                connected_squads=tariff.allowed_squads or [],
+                connected_squads=squads,
                 is_trial=False,
                 update_server_counters=True,
                 commit=False,
@@ -908,7 +924,7 @@ async def activate_purchase(db: AsyncSession, purchase_token: str, *, skip_notif
                 duration_days=purchase.period_days,
                 traffic_limit_gb=tariff.traffic_limit_gb,
                 device_limit=tariff.device_limit,
-                connected_squads=tariff.allowed_squads or [],
+                connected_squads=squads,
                 tariff_id=tariff.id,
                 update_server_counters=True,
                 commit=False,

app/services/monitoring_service.py

@@ -1053,8 +1053,11 @@ class MonitoringService:
                     autopay_period = 30
 
                 try:
+                    from app.database.crud.user import lock_user_for_pricing
                     from app.services.pricing_engine import pricing_engine
 
+                    user = await lock_user_for_pricing(db, user.id)
+
                     pricing = await pricing_engine.calculate_renewal_price(
                         db,
                         subscription,

app/services/payment/stars.py

@@ -260,6 +260,14 @@ class TelegramStarsMixin:
             logger.error('Не удалось активировать pending подписку пользователя', user_id=user.id)
             return False
 
+        # Consume promo-offer discount (invoice was created with discounted price)
+        try:
+            from app.utils.promo_offer import consume_user_promo_offer
+
+            await consume_user_promo_offer(db, user.id)
+        except Exception as promo_error:
+            logger.warning('Ошибка потребления промо-оффера при Stars оплате', user_id=user.id, error=promo_error)
+
         try:
             from app.services.subscription_service import SubscriptionService
 

app/services/payment/yookassa.py

@@ -912,6 +912,18 @@ class YooKassaPaymentMixin:
                         if subscription:
                             logger.info('Подписка успешно активирована для пользователя', user_id=user.id)
 
+                            # Consume promo-offer discount (invoice was created with discounted price)
+                            try:
+                                from app.utils.promo_offer import consume_user_promo_offer
+
+                                await consume_user_promo_offer(db, user.id)
+                            except Exception as promo_error:
+                                logger.warning(
+                                    'Ошибка потребления промо-оффера при YooKassa оплате',
+                                    user_id=user.id,
+                                    error=promo_error,
+                                )
+
                             # Обновляем данные подписки в RemnaWave, чтобы получить актуальные ссылки
                             try:
                                 remnawave_user = await subscription_service.create_remnawave_user(db, subscription)

app/services/payment_verification_service.py

@@ -242,12 +242,23 @@ class AutoPaymentVerificationService:
                 )
 
                 for record in candidates:
-                    refreshed = await run_manual_check(
-                        session,
-                        record.method,
-                        record.local_id,
-                        self._payment_service,
-                    )
+                    try:
+                        refreshed = await run_manual_check(
+                            session,
+                            record.method,
+                            record.local_id,
+                            self._payment_service,
+                        )
+                    except Exception as check_error:
+                        logger.error(
+                            'Ошибка проверки платежа, откатываем сессию',
+                            method_display_name=method_display_name(record.method),
+                            identifier=record.identifier,
+                            error=check_error,
+                        )
+                        if session.in_transaction():
+                            await session.rollback()
+                        continue
 
                     if not refreshed:
                         logger.debug(
@@ -972,6 +983,9 @@ async def run_manual_check(
             error=error,
             exc_info=True,
         )
+        # Откатываем сессию чтобы не оставлять её в грязном состоянии
+        if db.in_transaction():
+            await db.rollback()
         return None
 
 

app/services/pricing_engine.py

@@ -15,7 +15,7 @@ from app.utils.promo_offer import get_user_active_promo_discount_percent
 if TYPE_CHECKING:
     from sqlalchemy.ext.asyncio import AsyncSession
 
-    from app.database.models import Subscription, User
+    from app.database.models import Subscription, Tariff, User
 
 
 logger = structlog.get_logger(__name__)
@@ -27,8 +27,9 @@ class TariffBreakdown:
 
     tariff_id: int
     extra_devices: int
-    group_discount_pct: int
+    group_discount_pct: dict[str, int]
     offer_discount_pct: int
+    months_in_period: int = 1
 
 
 @dataclass(frozen=True)
@@ -42,9 +43,14 @@ class ClassicBreakdown:
     base_traffic_gb: int
     purchased_traffic_gb: int
     extra_devices: int
-    # NB: dict[str, int] per-category (period/servers/traffic/devices), unlike TariffBreakdown's single int
+    # Per-category discount percents (period/servers/traffic/devices)
     group_discount_pct: dict[str, int]
     offer_discount_pct: int
+    # Original (pre-discount) prices — used by classic_pricing_to_purchase_details()
+    base_price_original: int = 0
+    traffic_price_per_month: int = 0
+    servers_price_per_month: int = 0
+    devices_price_per_month: int = 0
 
 
 @dataclass(frozen=True)
@@ -68,6 +74,30 @@ class RenewalPricing:
         return self.final_total + self.promo_group_discount + self.promo_offer_discount
 
 
+@dataclass(frozen=True)
+class TariffSwitchResult:
+    """Immutable result of a tariff switch cost calculation."""
+
+    upgrade_cost: int  # kopeks — amount to charge (0 if downgrade/same)
+    is_upgrade: bool  # True if new tariff is more expensive
+    raw_cost: int  # kopeks — cost before discounts (for UI display)
+    group_discount_pct: int
+    offer_discount_pct: int
+    new_period_days: int = 0  # 0 = keep current end date, >0 = set new subscription period
+
+    @property
+    def discount_value(self) -> int:
+        """Сумма скидки в копейках."""
+        return self.raw_cost - self.upgrade_cost
+
+    @property
+    def effective_discount_pct(self) -> int:
+        """Эффективный процент скидки (стекинг group + offer)."""
+        if self.raw_cost <= 0:
+            return 0
+        return round(self.discount_value * 100 / self.raw_cost)
+
+
 class PricingEngine:
     """Unified pricing engine for all subscription renewal calculations."""
 
@@ -93,6 +123,286 @@ class PricingEngine:
         offer_discount_value = after_group - after_offer
         return after_offer, group_discount_value, offer_discount_value
 
+    @staticmethod
+    def resolve_promo_group(user: User | None):
+        """Resolve primary promo group: get_primary_promo_group() first, fallback to user.promo_group."""
+        if not user:
+            return None
+        if hasattr(user, 'get_primary_promo_group'):
+            pg = user.get_primary_promo_group()
+            if pg is not None:
+                return pg
+        return getattr(user, 'promo_group', None)
+
+    @staticmethod
+    def get_addon_discount_percent(
+        user: User | None,
+        category: str,
+        period_days_hint: int | None = None,
+        *,
+        promo_group: PromoGroup | None = None,
+    ) -> int:
+        """Return addon discount percent for a given category.
+
+        Uses promo_group.get_discount_percent() which handles is_default fallback.
+        Checks apply_discounts_to_addons flag. Returns 0 if no discount.
+
+        If promo_group is provided explicitly, it takes precedence over
+        resolving from user (useful when caller already resolved the group).
+        """
+        if promo_group is None:
+            if not user:
+                return 0
+            promo_group = PricingEngine.resolve_promo_group(user)
+
+        if not promo_group:
+            return 0
+
+        if not getattr(promo_group, 'apply_discounts_to_addons', True):
+            return 0
+
+        if hasattr(promo_group, 'get_discount_percent'):
+            return promo_group.get_discount_percent(category, period_days_hint)
+
+        # Fallback for promo groups without get_discount_percent
+        mapping = {
+            'traffic': 'traffic_discount_percent',
+            'servers': 'server_discount_percent',
+            'devices': 'device_discount_percent',
+        }
+        attr = mapping.get(category)
+        if attr:
+            return max(0, min(100, int(getattr(promo_group, attr, 0) or 0)))
+        return 0
+
+    @staticmethod
+    def calculate_traffic_discount(
+        base_price: int,
+        user: User | None,
+        period_days_hint: int | None = None,
+    ) -> tuple[int, int, int]:
+        """Apply traffic addon discount from user's promo group.
+
+        Checks apply_discounts_to_addons flag. Uses integer arithmetic.
+        Uses get_discount_percent() for correct is_default fallback.
+        Returns: (final_price, discount_value, discount_percent).
+        """
+        if not user or base_price <= 0:
+            return base_price, 0, 0
+
+        pct = PricingEngine.get_addon_discount_percent(user, 'traffic', period_days_hint)
+        if pct <= 0:
+            return base_price, 0, 0
+
+        final = PricingEngine.apply_discount(base_price, pct)
+        return final, base_price - final, pct
+
+    # ------------------------------------------------------------------
+    # Tariff switch
+    # ------------------------------------------------------------------
+
+    @staticmethod
+    def get_tariff_daily_rate_fraction(tariff: Tariff, target_days: int) -> tuple[int, int]:
+        """Дневная ставка тарифа как (price, period_days) для целочисленных вычислений.
+
+        Возвращает числитель и знаменатель дроби price/period_days,
+        чтобы избежать float-ошибок в финансовых расчётах.
+        """
+        periods = tariff.get_available_periods()
+        if not periods:
+            return 0, 1
+        best_period = min(periods, key=lambda p: abs(p - target_days))
+        price = tariff.get_price_for_period(best_period)
+        if not price or best_period <= 0:
+            return 0, 1
+        return price, best_period
+
+    def calculate_tariff_switch_cost(
+        self,
+        current_tariff: Tariff,
+        new_tariff: Tariff,
+        remaining_days: int,
+        *,
+        user: User | None = None,
+    ) -> TariffSwitchResult:
+        """Рассчитывает стоимость переключения тарифа.
+
+        Автоматически определяет тип переключения:
+        - periodic→daily: оплата первого дня (daily_price_kopeks)
+        - daily→periodic: оплата кратчайшего периода нового тарифа
+        - periodic→periodic: пропорциональная разница дневных ставок × remaining_days
+
+        Для всех типов переключений скидки (group + offer) применяются stacked.
+        """
+        current_is_daily = getattr(current_tariff, 'is_daily', False) if current_tariff else False
+        new_is_daily = getattr(new_tariff, 'is_daily', False)
+
+        # Daily tariff edge cases
+        if not current_is_daily and new_is_daily:
+            return self._calculate_switch_to_daily(new_tariff, remaining_days, user=user)
+        if current_is_daily and not new_is_daily:
+            return self._calculate_switch_from_daily(new_tariff, remaining_days, user=user)
+        if current_is_daily and new_is_daily:
+            # Daily → Daily: бесплатное переключение, cron начислит новую цену завтра
+            return TariffSwitchResult(
+                upgrade_cost=0,
+                is_upgrade=False,
+                raw_cost=0,
+                group_discount_pct=0,
+                offer_discount_pct=0,
+                new_period_days=1,
+            )
+
+        # --- Periodic → Periodic ---
+
+        # Early return: нечего считать при нулевом остатке
+        if remaining_days <= 0:
+            return TariffSwitchResult(
+                upgrade_cost=0,
+                is_upgrade=False,
+                raw_cost=0,
+                group_discount_pct=0,
+                offer_discount_pct=0,
+                new_period_days=0,
+            )
+
+        # Целочисленная арифметика (без float round-trip):
+        # raw_cost = (new_p/new_d - cur_p/cur_d) * remaining
+        #          = (new_p * cur_d - cur_p * new_d) * remaining / (new_d * cur_d)
+        # Floor division (//) округляет дробные копейки вниз — в пользу пользователя.
+        cur_price, cur_period = self.get_tariff_daily_rate_fraction(current_tariff, remaining_days)
+        new_price, new_period = self.get_tariff_daily_rate_fraction(new_tariff, remaining_days)
+
+        numerator = (new_price * cur_period - cur_price * new_period) * remaining_days
+        denominator = new_period * cur_period
+        raw_cost = max(0, numerator // denominator)
+
+        if numerator <= 0:
+            return TariffSwitchResult(
+                upgrade_cost=0,
+                is_upgrade=False,
+                raw_cost=0,
+                group_discount_pct=0,
+                offer_discount_pct=0,
+                new_period_days=0,
+            )
+
+        # Resolve discounts via resolve_promo_group (get_primary_promo_group first)
+        group_pct = 0
+        offer_pct = 0
+        if user:
+            promo_group = self.resolve_promo_group(user)
+            if promo_group is not None:
+                best_period = min(
+                    current_tariff.get_available_periods() or [30],
+                    key=lambda p: abs(p - remaining_days),
+                )
+                group_pct = promo_group.get_discount_percent('period', best_period)
+            offer_pct = get_user_active_promo_discount_percent(user)
+
+        # Применяем stacked скидки к итоговой сумме напрямую (без float round-trip)
+        if group_pct > 0 or offer_pct > 0:
+            upgrade_cost, _, _ = self.apply_stacked_discounts(raw_cost, group_pct, offer_pct)
+        else:
+            upgrade_cost = raw_cost
+
+        return TariffSwitchResult(
+            upgrade_cost=upgrade_cost,
+            is_upgrade=True,
+            raw_cost=raw_cost,
+            group_discount_pct=group_pct,
+            offer_discount_pct=offer_pct,
+            new_period_days=0,
+        )
+
+    def _calculate_switch_to_daily(
+        self,
+        new_tariff: Tariff,
+        remaining_days: int,
+        *,
+        user: User | None = None,
+    ) -> TariffSwitchResult:
+        """Periodic → Daily: оплата первого дня с group + offer discount."""
+        daily_price = getattr(new_tariff, 'daily_price_kopeks', 0) or 0
+        if daily_price <= 0:
+            return TariffSwitchResult(
+                upgrade_cost=0,
+                is_upgrade=False,
+                raw_cost=0,
+                group_discount_pct=0,
+                offer_discount_pct=0,
+                new_period_days=1,
+            )
+
+        group_pct = 0
+        offer_pct = 0
+        if user:
+            promo_group = self.resolve_promo_group(user)
+            if promo_group:
+                period_hint = remaining_days if remaining_days > 0 else 30
+                group_pct = promo_group.get_discount_percent('period', period_hint)
+            offer_pct = get_user_active_promo_discount_percent(user)
+
+        if group_pct > 0 or offer_pct > 0:
+            upgrade_cost, _, _ = self.apply_stacked_discounts(daily_price, group_pct, offer_pct)
+        else:
+            upgrade_cost = daily_price
+
+        return TariffSwitchResult(
+            upgrade_cost=upgrade_cost,
+            is_upgrade=upgrade_cost > 0,
+            raw_cost=daily_price,
+            group_discount_pct=group_pct,
+            offer_discount_pct=offer_pct,
+            new_period_days=1,
+        )
+
+    def _calculate_switch_from_daily(
+        self,
+        new_tariff: Tariff,
+        remaining_days: int,
+        *,
+        user: User | None = None,
+    ) -> TariffSwitchResult:
+        """Daily → Periodic: оплата кратчайшего периода нового тарифа с group + offer discount."""
+        min_period_days = 30
+        min_period_price = 0
+        if new_tariff.period_prices:
+            min_period_days = min(int(k) for k in new_tariff.period_prices.keys())
+            min_period_price = new_tariff.period_prices.get(str(min_period_days), 0) or 0
+
+        if min_period_price <= 0:
+            return TariffSwitchResult(
+                upgrade_cost=0,
+                is_upgrade=False,
+                raw_cost=0,
+                group_discount_pct=0,
+                offer_discount_pct=0,
+                new_period_days=min_period_days,
+            )
+
+        group_pct = 0
+        offer_pct = 0
+        if user:
+            promo_group = self.resolve_promo_group(user)
+            if promo_group:
+                group_pct = promo_group.get_discount_percent('period', min_period_days)
+            offer_pct = get_user_active_promo_discount_percent(user)
+
+        if group_pct > 0 or offer_pct > 0:
+            upgrade_cost, _, _ = self.apply_stacked_discounts(min_period_price, group_pct, offer_pct)
+        else:
+            upgrade_cost = min_period_price
+
+        return TariffSwitchResult(
+            upgrade_cost=upgrade_cost,
+            is_upgrade=upgrade_cost > 0,
+            raw_cost=min_period_price,
+            group_discount_pct=group_pct,
+            offer_discount_pct=offer_pct,
+            new_period_days=min_period_days,
+        )
+
     async def _calculate_servers_price(
         self,
         country_uuids: list[str],
@@ -222,37 +532,99 @@ class PricingEngine:
     ) -> RenewalPricing:
         """Price calculation when subscription is linked to a Tariff."""
         tariff = subscription.tariff
-        period_prices: dict = tariff.period_prices or {}
-        base_price = int(period_prices.get(str(period_days), 0) or 0)
+        device_limit = subscription.device_limit or 0
+        return await self._calculate_tariff_core(
+            tariff,
+            period_days,
+            device_limit,
+            user=user,
+        )
 
-        # Extra devices above the tariff's included limit
+    async def _calculate_tariff_core(
+        self,
+        tariff: Tariff,
+        period_days: int,
+        device_limit: int,
+        *,
+        custom_traffic_gb: int | None = None,
+        user: User | None = None,
+    ) -> RenewalPricing:
+        """Core tariff pricing logic (raw params, no Subscription needed).
+
+        Per-category discounts:
+        - 'period' → base tariff price
+        - 'devices' → extra device cost
+        Promo-offer discount applied on the discounted subtotal.
+        Device cost is monthly × months_in_period.
+        """
+        months = calculate_months_from_days(period_days)
+
+        # --- Base price ---
+        is_daily = getattr(tariff, 'is_daily', False)
+        if is_daily and period_days <= 1:
+            base_price = int(getattr(tariff, 'daily_price_kopeks', 0) or 0)
+        else:
+            period_prices: dict = tariff.period_prices or {}
+            base_price = int(period_prices.get(str(period_days), 0) or 0)
+            if base_price == 0 and hasattr(tariff, 'get_price_for_custom_days'):
+                if hasattr(tariff, 'can_purchase_custom_days') and tariff.can_purchase_custom_days():
+                    custom_price = tariff.get_price_for_custom_days(period_days)
+                    if custom_price is not None:
+                        base_price = int(custom_price)
+
+        # --- Extra devices (monthly × months) ---
         device_price_per_unit = (
             tariff.device_price_kopeks if tariff.device_price_kopeks is not None else settings.PRICE_PER_DEVICE
         )
-        extra_devices = max(0, (subscription.device_limit or 0) - (tariff.device_limit or 0))
-        devices_price = extra_devices * device_price_per_unit
+        tariff_device_limit = tariff.device_limit or 0
+        extra_devices = max(0, (device_limit or 0) - tariff_device_limit)
+        if is_daily and period_days <= 1:
+            devices_price = extra_devices * device_price_per_unit
+        else:
+            devices_price = extra_devices * device_price_per_unit * months
 
-        subtotal = base_price + devices_price
+        # --- Custom traffic (tariff add-on, uses addon discount path) ---
+        traffic_price = 0
+        if custom_traffic_gb is not None and hasattr(tariff, 'get_price_for_custom_traffic'):
+            raw_traffic = tariff.get_price_for_custom_traffic(custom_traffic_gb)
+            if raw_traffic and raw_traffic > 0:
+                traffic_price = int(raw_traffic)
 
-        # Resolve discounts
-        group_pct = 0
-        if user and getattr(user, 'promo_group', None) is not None:
-            group_pct = user.promo_group.get_discount_percent('period', period_days)
+        # --- Per-category group discounts ---
+        period_pct = 0
+        devices_pct = 0
+        promo_group = self.resolve_promo_group(user)
+        if promo_group is not None:
+            period_pct = promo_group.get_discount_percent('period', period_days)
+            devices_pct = promo_group.get_discount_percent('devices', period_days)
 
         offer_pct = get_user_active_promo_discount_percent(user) if user else 0
 
-        final_total, group_discount, offer_discount = self.apply_stacked_discounts(
-            subtotal,
-            group_pct,
-            offer_pct,
-        )
+        discounted_base = self.apply_discount(base_price, period_pct)
+        discounted_devices = self.apply_discount(devices_price, devices_pct)
+
+        # Traffic uses addon discount (checks apply_discounts_to_addons flag)
+        discounted_traffic = traffic_price
+        if traffic_price > 0 and user:
+            discounted_traffic, _, _ = self.calculate_traffic_discount(traffic_price, user)
+
+        base_group_disc = base_price - discounted_base
+        devices_group_disc = devices_price - discounted_devices
+        traffic_group_disc = traffic_price - discounted_traffic
+        total_group_discount = base_group_disc + devices_group_disc + traffic_group_disc
+
+        subtotal = discounted_base + discounted_devices + discounted_traffic
+        after_offer = self.apply_discount(subtotal, offer_pct)
+        offer_discount = subtotal - after_offer
+        final_total = after_offer
 
         breakdown = dataclasses.asdict(
             TariffBreakdown(
                 tariff_id=tariff.id,
                 extra_devices=extra_devices,
-                group_discount_pct=group_pct,
+                group_discount_pct={'period': period_pct, 'devices': devices_pct},
                 offer_discount_pct=offer_pct,
+                months_in_period=months,
             )
         )
 
@@ -261,16 +633,17 @@ class PricingEngine:
                 'Negative final_total in tariff mode, clamping to 0',
                 final_total=final_total,
                 subtotal=subtotal,
-                group_pct=group_pct,
+                period_pct=period_pct,
+                devices_pct=devices_pct,
                 offer_pct=offer_pct,
             )
 
         return RenewalPricing(
-            base_price=base_price,
+            base_price=discounted_base,
             servers_price=0,
-            traffic_price=0,
-            devices_price=devices_price,
-            promo_group_discount=group_discount,
+            traffic_price=discounted_traffic,
+            devices_price=discounted_devices,
+            promo_group_discount=total_group_discount,
             promo_offer_discount=offer_discount,
             final_total=max(0, final_total),
             period_days=period_days,
@@ -278,19 +651,45 @@ class PricingEngine:
             breakdown=breakdown,
         )
 
+    async def calculate_tariff_purchase_price(
+        self,
+        tariff: Tariff,
+        period_days: int,
+        *,
+        device_limit: int | None = None,
+        custom_traffic_gb: int | None = None,
+        user: User | None = None,
+    ) -> RenewalPricing:
+        """Calculate price for a tariff purchase (new or renewal).
+
+        Public method that delegates to _calculate_tariff_core.
+        If device_limit is None, uses the tariff's included limit (no extra devices).
+        """
+        effective_device_limit = device_limit if device_limit is not None else (tariff.device_limit or 0)
+        return await self._calculate_tariff_core(
+            tariff,
+            period_days,
+            effective_device_limit,
+            custom_traffic_gb=custom_traffic_gb,
+            user=user,
+        )
+
     # ------------------------------------------------------------------
     # Classic mode
     # ------------------------------------------------------------------
 
-    async def _calculate_classic_mode(
+    async def _calculate_classic_core(
         self,
         db: AsyncSession,
-        subscription: Subscription,
         period_days: int,
+        connected_squads: list[str],
+        traffic_limit_gb: int,
+        device_limit: int,
         *,
+        purchased_traffic_gb: int = 0,
         user: User | None = None,
     ) -> RenewalPricing:
-        """Price calculation for legacy (non-tariff) subscriptions.
+        """Core classic-mode pricing logic (raw params, no Subscription needed).
 
         Uses CLASSIC_PERIOD_PRICES from settings, falling back to the
         global PERIOD_PRICES dict during migration.
@@ -298,6 +697,7 @@ class PricingEngine:
         Per-category discounts (period, servers, traffic, devices) are
         applied separately to each component. Servers, traffic, and
         devices are monthly prices multiplied by months_in_period.
+        Promo-offer discount is applied on the subtotal.
         """
         months = calculate_months_from_days(period_days)
 
@@ -312,14 +712,13 @@ class PricingEngine:
                     fallback_price_kopeks=base_price_original,
                 )
 
-        # --- Per-category discount percents ---
+        # --- Per-category discount percents (resolve_promo_group: get_primary_promo_group first) ---
         period_pct = 0
         servers_pct = 0
         traffic_pct = 0
         devices_pct = 0
-        promo_group = None
-        if user and getattr(user, 'promo_group', None) is not None:
-            promo_group = user.promo_group
+        promo_group = self.resolve_promo_group(user)
+        if promo_group is not None:
             period_pct = promo_group.get_discount_percent('period', period_days)
             servers_pct = promo_group.get_discount_percent('servers', period_days)
             traffic_pct = promo_group.get_discount_percent('traffic', period_days)
@@ -331,7 +730,6 @@ class PricingEngine:
         base_price = self.apply_discount(base_price_original, period_pct)
 
         # --- Servers (monthly × months, with servers discount) ---
-        connected_squads: list[str] = subscription.connected_squads or []
         promo_group_id = getattr(user, 'promo_group_id', None) if user else None
         servers_price_per_month, server_details = await self._calculate_servers_price(
             connected_squads,
@@ -345,13 +743,6 @@ class PricingEngine:
         if settings.is_traffic_fixed():
             traffic_limit_gb = settings.get_fixed_traffic_limit()
             purchased_traffic_gb = 0
-        else:
-            traffic_limit_gb = (
-                subscription.traffic_limit_gb
-                if subscription.traffic_limit_gb is not None
-                else settings.DEFAULT_TRAFFIC_LIMIT_GB
-            )
-            purchased_traffic_gb = subscription.purchased_traffic_gb or 0
         traffic_price_per_month = self._calculate_traffic_price(traffic_limit_gb, purchased_traffic_gb)
         discounted_traffic_per_month = self.apply_discount(traffic_price_per_month, traffic_pct)
         traffic_price = discounted_traffic_per_month * months
@@ -359,7 +750,7 @@ class PricingEngine:
         # --- Devices (monthly × months, with devices discount) ---
         default_device_limit = settings.DEFAULT_DEVICE_LIMIT
         device_price_per_unit = settings.PRICE_PER_DEVICE
-        extra_devices = max(0, (subscription.device_limit or 0) - default_device_limit)
+        extra_devices = max(0, (device_limit or 0) - default_device_limit)
         devices_price_per_month = extra_devices * device_price_per_unit
         discounted_devices_per_month = self.apply_discount(devices_price_per_month, devices_pct)
         devices_price = discounted_devices_per_month * months
@@ -386,7 +777,9 @@ class PricingEngine:
             ClassicBreakdown(
                 months_in_period=months,
                 servers=server_details,
-                servers_individual_prices=[d['price'] * months for d in valid_servers],
+                servers_individual_prices=[
+                    self.apply_discount(d['price'], servers_pct) * months for d in valid_servers
+                ],
                 server_ids=[d['id'] for d in valid_servers],
                 base_traffic_gb=max(0, traffic_limit_gb - purchased_traffic_gb),
                 purchased_traffic_gb=purchased_traffic_gb,
@@ -398,6 +791,10 @@ class PricingEngine:
                     'devices': devices_pct,
                 },
                 offer_discount_pct=offer_pct,
+                base_price_original=base_price_original,
+                traffic_price_per_month=traffic_price_per_month,
+                servers_price_per_month=servers_price_per_month,
+                devices_price_per_month=devices_price_per_month,
             )
         )
 
@@ -422,6 +819,116 @@ class PricingEngine:
             breakdown=breakdown,
         )
 
+    async def _calculate_classic_mode(
+        self,
+        db: AsyncSession,
+        subscription: Subscription,
+        period_days: int,
+        *,
+        user: User | None = None,
+    ) -> RenewalPricing:
+        """Price calculation for legacy (non-tariff) subscriptions.
+
+        Thin wrapper that extracts raw params from a Subscription
+        and delegates to _calculate_classic_core.
+        """
+        connected_squads: list[str] = subscription.connected_squads or []
+        traffic_limit_gb = (
+            subscription.traffic_limit_gb
+            if subscription.traffic_limit_gb is not None
+            else settings.DEFAULT_TRAFFIC_LIMIT_GB
+        )
+        purchased_traffic_gb = subscription.purchased_traffic_gb or 0
+        device_limit = subscription.device_limit or 0
+
+        return await self._calculate_classic_core(
+            db,
+            period_days,
+            connected_squads,
+            traffic_limit_gb,
+            device_limit,
+            purchased_traffic_gb=purchased_traffic_gb,
+            user=user,
+        )
+
+    async def calculate_classic_new_subscription_price(
+        self,
+        db: AsyncSession,
+        period_days: int,
+        connected_squads: list[str],
+        traffic_limit_gb: int,
+        device_limit: int,
+        *,
+        user: User | None = None,
+    ) -> RenewalPricing:
+        """Calculate price for a NEW classic (non-tariff) subscription.
+
+        Like calculate_renewal_price but without requiring an existing
+        Subscription object. purchased_traffic_gb is always 0.
+        """
+        return await self._calculate_classic_core(
+            db,
+            period_days,
+            connected_squads,
+            traffic_limit_gb,
+            device_limit,
+            purchased_traffic_gb=0,
+            user=user,
+        )
+
+    @staticmethod
+    def classic_pricing_to_purchase_details(pricing: RenewalPricing) -> dict[str, Any]:
+        """Convert RenewalPricing to the legacy details dict format.
+
+        The returned dict is compatible with build_preview_payload
+        in SubscriptionPurchaseService.
+        """
+        bd = pricing.breakdown
+        months = bd.get('months_in_period', 1) or 1
+        group_pct = bd.get('group_discount_pct', {})
+
+        base_price_original = bd.get('base_price_original', 0)
+        traffic_price_per_month = bd.get('traffic_price_per_month', 0)
+        servers_price_per_month = bd.get('servers_price_per_month', 0)
+        devices_price_per_month = bd.get('devices_price_per_month', 0)
+
+        period_pct = group_pct.get('period', 0)
+        traffic_pct = group_pct.get('traffic', 0)
+        servers_pct = group_pct.get('servers', 0)
+        devices_pct = group_pct.get('devices', 0)
+
+        base_discount_total = base_price_original - pricing.base_price
+        traffic_discount_total = (
+            traffic_price_per_month - PricingEngine.apply_discount(traffic_price_per_month, traffic_pct)
+        ) * months
+        servers_discount_total = (
+            servers_price_per_month - PricingEngine.apply_discount(servers_price_per_month, servers_pct)
+        ) * months
+        devices_discount_total = (
+            devices_price_per_month - PricingEngine.apply_discount(devices_price_per_month, devices_pct)
+        ) * months
+
+        return {
+            'base_price': pricing.base_price,
+            'base_price_original': base_price_original,
+            'base_discount_percent': period_pct,
+            'base_discount_total': base_discount_total,
+            'traffic_price_per_month': traffic_price_per_month,
+            'traffic_discount_percent': traffic_pct,
+            'traffic_discount_total': traffic_discount_total,
+            'total_traffic_price': pricing.traffic_price,
+            'servers_price_per_month': servers_price_per_month,
+            'servers_discount_percent': servers_pct,
+            'servers_discount_total': servers_discount_total,
+            'total_servers_price': pricing.servers_price,
+            'devices_price_per_month': devices_price_per_month,
+            'devices_discount_percent': devices_pct,
+            'devices_discount_total': devices_discount_total,
+            'total_devices_price': pricing.devices_price,
+            'months_in_period': months,
+            'servers_individual_prices': bd.get('servers_individual_prices', []),
+        }
+
 
 # Module-level singleton — use this instead of PricingEngine()
 pricing_engine = PricingEngine()

app/services/recurrent_payment_service.py

@@ -224,8 +224,12 @@ async def _process_single_subscription(
         autopay_period = 30
 
     try:
+        from app.database.crud.user import lock_user_for_pricing
         from app.services.pricing_engine import pricing_engine
 
+        # TOCTOU: lock user row before pricing to prevent concurrent promo/balance races
+        user = await lock_user_for_pricing(db, user.id)
+
         pricing = await pricing_engine.calculate_renewal_price(
             db,
             subscription,

app/services/subscription_auto_purchase_service.py

@@ -14,7 +14,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from app.config import settings
 from app.database.crud.subscription import extend_subscription
 from app.database.crud.transaction import create_transaction
-from app.database.crud.user import get_user_by_id, subtract_user_balance
+from app.database.crud.user import subtract_user_balance
 from app.database.models import Subscription, SubscriptionStatus, TransactionType, User
 from app.localization.texts import get_texts
 from app.services.admin_notification_service import AdminNotificationService
@@ -83,13 +83,11 @@ async def _prepare_auto_purchase(
         )
         return None
 
-    # Перезагружаем user с нужными связями (user_promo_groups),
+    # Блокируем user с нужными связями (user_promo_groups) для защиты от TOCTOU,
     # т.к. после db.refresh() в payment-сервисах связи сбрасываются
-    fresh_user = await get_user_by_id(db, user.id)
-    if not fresh_user:
-        logger.warning('🔁 Автопокупка: не удалось перезагрузить пользователя', format_user_id=_format_user_id(user))
-        return None
-    user = fresh_user
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
 
     miniapp_service = MiniAppSubscriptionPurchaseService()
     context = await miniapp_service.build_options(db, user)
@@ -141,11 +139,6 @@ def _safe_int(value: object | None, default: int = 0) -> int:
         return default
 
 
-def _apply_promo_discount_for_tariff(price: int, discount_percent: int) -> int:
-    """Применяет скидку промогруппы к цене тарифа."""
-    return PricingEngine.apply_discount(price, discount_percent)
-
-
 async def _prepare_auto_extend_context(
     db: AsyncSession,
     user: User,
@@ -187,7 +180,11 @@ async def _prepare_auto_extend_context(
     if tariff_id:
         tariff_id = _safe_int(tariff_id)
 
+    from app.database.crud.user import lock_user_for_pricing
     from app.services.pricing_engine import pricing_engine as _pricing_engine
+    from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+    user = await lock_user_for_pricing(db, user.id)
 
     try:
         pricing = await _pricing_engine.calculate_renewal_price(
@@ -232,8 +229,6 @@ async def _prepare_auto_extend_context(
         traffic_limit_gb = _safe_int(traffic_limit_gb, subscription.traffic_limit_gb or 0)
 
     squad_uuid = cart_data.get('squad_uuid')
-    from app.utils.promo_offer import get_user_active_promo_discount_percent
-
     consume_promo_offer = get_user_active_promo_discount_percent(user) > 0
     allowed_squads = cart_data.get('allowed_squads')
 
@@ -625,44 +620,26 @@ async def _auto_purchase_tariff(
         )
         return False
 
-    # Получаем актуальную цену тарифа
-    prices = tariff.period_prices or {}
-    base_price = prices.get(str(period_days))
-    if base_price is None:
-        logger.warning(
-            '🔁 Автопокупка тарифа: период дней недоступен для тарифа', period_days=period_days, tariff_id=tariff_id
-        )
-        return False
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
 
-    final_price = int(base_price)
-
-    # Проверяем есть ли уже подписка (нужно до расчёта цены для учёта доп. устройств)
     existing_subscription = await get_subscription_by_user_id(db, user.id)
 
-    # Добавляем стоимость докупленных устройств ДО скидки (как в cabinet)
+    user = await lock_user_for_pricing(db, user.id)
+
+    # Calculate price via PricingEngine (single source of truth)
+    device_limit = None
     if existing_subscription and existing_subscription.tariff_id == tariff_id:
-        extra_devices = max(0, (existing_subscription.device_limit or 0) - (tariff.device_limit or 0))
-        if extra_devices > 0:
-            device_price_per_unit = (
-                tariff.device_price_kopeks if tariff.device_price_kopeks is not None else settings.PRICE_PER_DEVICE
-            )
-            extra_devices_cost = extra_devices * device_price_per_unit
-            final_price += extra_devices_cost
+        device_limit = existing_subscription.device_limit
 
-    # Пересчитываем скидку из актуальных данных пользователя (не из stale корзины)
-    # Promo_group и promo_offer применяются последовательно (как в cabinet)
-    from app.utils.promo_offer import get_user_active_promo_discount_percent
-
-    discount_percent = 0
-    if hasattr(user, 'get_promo_discount'):
-        discount_percent = user.get_promo_discount('period', period_days)
-
-    if discount_percent > 0:
-        final_price = _apply_promo_discount_for_tariff(final_price, discount_percent)
-
-    promo_offer_percent = get_user_active_promo_discount_percent(user)
-    if promo_offer_percent > 0:
-        final_price = _apply_promo_discount_for_tariff(final_price, promo_offer_percent)
+    result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        period_days,
+        device_limit=device_limit,
+        user=user,
+    )
+    final_price = result.final_total
+    consume_promo = result.promo_offer_discount > 0
 
     if user.balance_kopeks < final_price:
         logger.info(
@@ -674,7 +651,6 @@ async def _auto_purchase_tariff(
         return False
 
     # Save promo offer state before deduction (for restore on failure)
-    consume_promo = promo_offer_percent > 0
     saved_promo_percent = int(getattr(user, 'promo_offer_discount_percent', 0) or 0) if consume_promo else 0
     saved_promo_source = getattr(user, 'promo_offer_discount_source', None) if consume_promo else None
     saved_promo_expires = getattr(user, 'promo_offer_discount_expires_at', None) if consume_promo else None
@@ -978,12 +954,25 @@ async def _auto_purchase_daily_tariff(
         )
         return False
 
-    if user.balance_kopeks < daily_price:
+    # Блокируем пользователя и применяем скидки (group + promo-offer)
+    from app.database.crud.user import lock_user_for_pricing
+    from app.utils.promo_offer import get_user_active_promo_discount_percent
+
+    user = await lock_user_for_pricing(db, user.id)
+
+    promo_group = user.get_primary_promo_group()
+    group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+    offer_pct = get_user_active_promo_discount_percent(user)
+
+    final_price, _, _ = PricingEngine.apply_stacked_discounts(daily_price, group_pct, offer_pct)
+    consume_promo = offer_pct > 0
+
+    if user.balance_kopeks < final_price:
         logger.info(
             '🔁 Автопокупка суточного тарифа: у пользователя недостаточно средств (<)',
             format_user_id=_format_user_id(user),
             balance_kopeks=user.balance_kopeks,
-            daily_price=daily_price,
+            final_price=final_price,
         )
         return False
 
@@ -993,8 +982,9 @@ async def _auto_purchase_daily_tariff(
         success = await subtract_user_balance(
             db,
             user,
-            daily_price,
+            final_price,
             description,
+            consume_promo_offer=consume_promo,
             mark_as_paid_subscription=True,
         )
         if not success:
@@ -1081,7 +1071,7 @@ async def _auto_purchase_daily_tariff(
             await add_user_balance(
                 db,
                 user,
-                daily_price,
+                final_price,
                 'Возврат: ошибка автопокупки суточного тарифа',
                 create_transaction=True,
                 transaction_type=TransactionType.REFUND,
@@ -1089,13 +1079,13 @@ async def _auto_purchase_daily_tariff(
             logger.info(
                 '💰 Автопокупка суточного тарифа: возврат средств после ошибки создания подписки',
                 format_user_id=_format_user_id(user),
-                refund_kopeks=daily_price,
+                refund_kopeks=final_price,
             )
         except Exception as refund_error:
             logger.critical(
                 'CRITICAL: Автопокупка суточного тарифа: не удалось вернуть средства',
                 format_user_id=_format_user_id(user),
-                price_kopeks=daily_price,
+                price_kopeks=final_price,
                 refund_error=refund_error,
             )
         return False
@@ -1106,7 +1096,7 @@ async def _auto_purchase_daily_tariff(
             db=db,
             user_id=user.id,
             type=TransactionType.SUBSCRIPTION_PAYMENT,
-            amount_kopeks=daily_price,
+            amount_kopeks=final_price,
             description=description,
         )
     except Exception as error:
@@ -1167,7 +1157,7 @@ async def _auto_purchase_daily_tariff(
 
             message = (
                 f'✅ <b>Суточный тариф «{tariff.name}» активирован!</b>\n\n'
-                f'💰 Списано: {daily_price / 100:.0f} ₽ за первый день\n'
+                f'💰 Списано: {final_price / 100:.0f} ₽ за первый день\n'
                 f'🔄 Средства будут списываться автоматически раз в сутки.\n\n'
                 f'ℹ️ Вы можете приостановить подписку в любой момент.'
             )
@@ -1215,7 +1205,7 @@ async def _auto_purchase_daily_tariff(
             await notify_user_subscription_renewed(
                 user_id=user.id,
                 new_expires_at=subscription.end_date.isoformat() if subscription.end_date else '',
-                amount_kopeks=daily_price,
+                amount_kopeks=final_price,
             )
         else:
             # New subscription activation
@@ -1244,28 +1234,19 @@ async def _auto_add_devices(
     """Auto-purchase devices from saved cart after balance topup."""
     from aiogram.types import InlineKeyboardButton, InlineKeyboardMarkup
 
-    from app.database.crud.user import subtract_user_balance
+    from app.database.crud.user import lock_user_for_pricing, subtract_user_balance
     from app.database.models import PaymentMethod
+    from app.utils.pricing_utils import apply_percentage_discount
 
     devices_to_add = _safe_int(cart_data.get('devices_to_add'))
-    price_kopeks = _safe_int(cart_data.get('price_kopeks'))
+    cart_price_kopeks = _safe_int(cart_data.get('price_kopeks'))
 
-    if devices_to_add <= 0 or price_kopeks <= 0:
+    if devices_to_add <= 0 or cart_price_kopeks <= 0:
         logger.warning(
             '🔁 Автопокупка устройств: некорректные данные корзины для пользователя (devices price=)',
             format_user_id=_format_user_id(user),
             devices_to_add=devices_to_add,
-            price_kopeks=price_kopeks,
-        )
-        return False
-
-    # Проверяем баланс
-    if user.balance_kopeks < price_kopeks:
-        logger.info(
-            '🔁 Автопокупка устройств: у пользователя недостаточно средств (<)',
-            format_user_id=_format_user_id(user),
-            balance_kopeks=user.balance_kopeks,
-            price_kopeks=price_kopeks,
+            cart_price_kopeks=cart_price_kopeks,
         )
         return False
 
@@ -1330,6 +1311,44 @@ async def _auto_add_devices(
         await user_cart_service.delete_user_cart(user.id)
         return False
 
+    # Lock user BEFORE price computation to prevent TOCTOU on promo-offer/group discount
+    user = await lock_user_for_pricing(db, user.id)
+
+    # Recompute price fresh under lock (pricing config may have changed since cart was saved)
+    devices_price_per_month = devices_to_add * tariff_device_price
+    days_left = max(1, (subscription.end_date - datetime.now(UTC)).days)
+    devices_discount_percent = PricingEngine.get_addon_discount_percent(
+        user,
+        'devices',
+        days_left,
+    )
+    discounted_per_month, _ = apply_percentage_discount(
+        devices_price_per_month,
+        devices_discount_percent,
+    )
+    price_kopeks = int(discounted_per_month * days_left / 30)
+    price_kopeks = max(100, price_kopeks)
+
+    if price_kopeks != cart_price_kopeks:
+        logger.warning(
+            '🔁 Автопокупка устройств: пересчитанная цена отличается от корзины',
+            format_user_id=_format_user_id(user),
+            cart_price_kopeks=cart_price_kopeks,
+            recomputed_price_kopeks=price_kopeks,
+            devices_discount_percent=devices_discount_percent,
+            days_left=days_left,
+        )
+
+    # Проверяем баланс (с актуальной ценой)
+    if user.balance_kopeks < price_kopeks:
+        logger.info(
+            '🔁 Автопокупка устройств: у пользователя недостаточно средств (<)',
+            format_user_id=_format_user_id(user),
+            balance_kopeks=user.balance_kopeks,
+            price_kopeks=price_kopeks,
+        )
+        return False
+
     # Списываем баланс
     description = f'Покупка {devices_to_add} доп. устройств'
     try:
@@ -1519,28 +1538,19 @@ async def _auto_add_traffic(
     from aiogram.types import InlineKeyboardButton, InlineKeyboardMarkup
 
     from app.database.crud.subscription import add_subscription_traffic, get_subscription_by_user_id
-    from app.database.crud.user import subtract_user_balance
+    from app.database.crud.user import lock_user_for_pricing, subtract_user_balance
     from app.database.models import PaymentMethod
+    from app.utils.pricing_utils import calculate_prorated_price
 
     traffic_gb = _safe_int(cart_data.get('traffic_gb'))
-    price_kopeks = _safe_int(cart_data.get('price_kopeks'))
+    cart_price_kopeks = _safe_int(cart_data.get('price_kopeks'))
 
-    if traffic_gb <= 0 or price_kopeks <= 0:
+    if traffic_gb <= 0 or cart_price_kopeks <= 0:
         logger.warning(
             '🔁 Автопокупка трафика: некорректные данные корзины для пользователя (traffic_gb price=)',
             format_user_id=_format_user_id(user),
             traffic_gb=traffic_gb,
-            price_kopeks=price_kopeks,
-        )
-        return False
-
-    # Verify balance
-    if user.balance_kopeks < price_kopeks:
-        logger.info(
-            '🔁 Автопокупка трафика: у пользователя недостаточно средств (<)',
-            format_user_id=_format_user_id(user),
-            balance_kopeks=user.balance_kopeks,
-            price_kopeks=price_kopeks,
+            cart_price_kopeks=cart_price_kopeks,
         )
         return False
 
@@ -1572,6 +1582,72 @@ async def _auto_add_traffic(
         await user_cart_service.delete_user_cart(user.id)
         return False
 
+    # Lock user BEFORE price computation to prevent TOCTOU on promo-offer/group discount
+    user = await lock_user_for_pricing(db, user.id)
+
+    # Recompute base price from tariff/settings (config may have changed since cart was saved)
+    tariff = None
+    if settings.is_tariffs_mode() and subscription.tariff_id:
+        from app.database.crud.tariff import get_tariff_by_id
+
+        tariff = await get_tariff_by_id(db, subscription.tariff_id)
+
+    if tariff and tariff.can_topup_traffic():
+        base_price = tariff.get_traffic_topup_price(traffic_gb) or 0
+    else:
+        base_price = settings.get_traffic_topup_price(traffic_gb)
+
+    if base_price <= 0 and traffic_gb != 0:
+        logger.warning(
+            '🔁 Автопокупка трафика: цена пакета не настроена, корзина удалена',
+            format_user_id=_format_user_id(user),
+            traffic_gb=traffic_gb,
+        )
+        await user_cart_service.delete_user_cart(user.id)
+        return False
+
+    # Apply traffic discount from promo group
+    period_hint_days: int | None = None
+    if subscription.end_date:
+        days_remaining = (subscription.end_date - datetime.now(UTC)).days
+        period_hint_days = days_remaining if days_remaining > 0 else None
+
+    discounted_per_month, _, _ = PricingEngine.calculate_traffic_discount(
+        base_price,
+        user,
+        period_hint_days,
+    )
+
+    # Prorate for classic mode (tariff mode uses monthly price as-is)
+    is_tariff_mode = settings.is_tariffs_mode() and subscription.tariff_id
+    if is_tariff_mode:
+        price_kopeks = discounted_per_month
+    elif subscription and subscription.end_date:
+        price_kopeks, _ = calculate_prorated_price(discounted_per_month, subscription.end_date)
+    else:
+        price_kopeks = discounted_per_month
+
+    if cart_price_kopeks != price_kopeks:
+        logger.warning(
+            '🔁 Автопокупка трафика: пересчитанная цена отличается от корзины',
+            format_user_id=_format_user_id(user),
+            cart_price_kopeks=cart_price_kopeks,
+            recomputed_price_kopeks=price_kopeks,
+            base_price=base_price,
+            discounted_per_month=discounted_per_month,
+            period_hint_days=period_hint_days,
+        )
+
+    # Verify balance (with fresh price)
+    if user.balance_kopeks < price_kopeks:
+        logger.info(
+            '🔁 Автопокупка трафика: у пользователя недостаточно средств (<)',
+            format_user_id=_format_user_id(user),
+            balance_kopeks=user.balance_kopeks,
+            price_kopeks=price_kopeks,
+        )
+        return False
+
     # Deduct balance
     description = f'Докупка {traffic_gb} ГБ трафика'
     try:
@@ -1801,6 +1877,11 @@ async def try_auto_extend_expired_after_topup(
     else:
         period_days = 30
 
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     # Calculate renewal price via PricingEngine
     subscription_service = SubscriptionService()
     try:
@@ -1870,10 +1951,8 @@ async def try_auto_extend_expired_after_topup(
             check_error=check_error,
         )
 
-    # Determine if promo offer discount was applied (for consume flag)
-    from app.utils.promo_offer import get_user_active_promo_discount_percent
-
-    consume_promo_offer = get_user_active_promo_discount_percent(user) > 0
+    # Derive consume_promo_offer from PricingEngine result (user already locked above)
+    consume_promo_offer = pricing.promo_offer_discount > 0
 
     # Save promo offer state before deduction (for restore on failure)
     saved_promo_percent = int(getattr(user, 'promo_offer_discount_percent', 0) or 0) if consume_promo_offer else 0
@@ -2142,11 +2221,25 @@ async def try_resume_disabled_daily_after_topup(
     if not tariff:
         return False
 
-    daily_price = getattr(tariff, 'daily_price_kopeks', 0)
-    if daily_price <= 0:
+    raw_daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+    if raw_daily_price <= 0:
         return False
 
-    # Check balance
+    # Lock user row to prevent TOCTOU between discount read and balance charge
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
+    # Apply group discount to daily price (consistent with PricingEngine._calculate_switch_to_daily)
+    from app.services.pricing_engine import PricingEngine
+
+    promo_group = PricingEngine.resolve_promo_group(user)
+    daily_group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+    daily_price = (
+        PricingEngine.apply_discount(raw_daily_price, daily_group_pct) if daily_group_pct > 0 else raw_daily_price
+    )
+
+    # Check balance (uses locked user's balance_kopeks — safe from concurrent reads)
     if user.balance_kopeks < daily_price:
         logger.info(
             '🔄 Авто-возобновление daily: недостаточно средств',

app/services/subscription_purchase_service.py

@@ -11,7 +11,6 @@ from app.config import PERIOD_PRICES, settings
 from app.database.crud.server_squad import (
     add_user_to_servers,
     get_available_server_squads,
-    get_server_ids_by_uuids,
     get_server_squad_by_uuid,
 )
 from app.database.crud.subscription import (
@@ -32,7 +31,6 @@ from app.utils.pricing_utils import (
     format_period_description,
     validate_pricing_calculation,
 )
-from app.utils.promo_offer import get_user_active_promo_discount_percent
 
 
 logger = structlog.get_logger(__name__)
@@ -279,18 +277,6 @@ def _apply_discount_to_monthly_component(amount_per_month: int, percent: int, mo
     }
 
 
-def _get_promo_offer_discount_percent(user: User | None) -> int:
-    return get_user_active_promo_discount_percent(user)
-
-
-def _apply_promo_offer_discount(user: User | None, amount: int) -> tuple[int, int, int]:
-    percent = _get_promo_offer_discount_percent(user)
-    if amount <= 0 or percent <= 0:
-        return amount, 0, 0
-    discounted, discount_value = apply_percentage_discount(amount, percent)
-    return discounted, discount_value, percent
-
-
 def _build_server_option(
     server: ServerSquad,
     discount_percent: int,
@@ -321,11 +307,9 @@ class MiniAppSubscriptionPurchaseService:
         currency = (getattr(user, 'balance_currency', None) or 'RUB').upper()
         texts = get_texts(getattr(user, 'language', None))
 
-        # Exclude trial-only servers from purchase options
         available_servers = await get_available_server_squads(
             db,
             promo_group_id=getattr(user, 'promo_group_id', None),
-            exclude_trial_only=True,
         )
         server_catalog: dict[str, ServerSquad] = {server.squad_uuid: server for server in available_servers}
 
@@ -711,29 +695,30 @@ class MiniAppSubscriptionPurchaseService:
         get_texts(getattr(context.user, 'language', None))
         months = selection.period.months
 
-        server_ids = await get_server_ids_by_uuids(db, selection.servers)
+        # PricingEngine — single source of truth (includes promo-offer internally).
+        # Server validation is done via breakdown (avoids a duplicate DB query).
+        from app.services.pricing_engine import PricingEngine, pricing_engine
+
+        pricing = await pricing_engine.calculate_classic_new_subscription_price(
+            db,
+            selection.period.days,
+            list(selection.servers),
+            selection.traffic_value,
+            selection.devices,
+            user=context.user,
+        )
+
+        # Validate all requested servers were found
+        server_ids = pricing.breakdown.get('server_ids', [])
         if len(server_ids) != len(selection.servers):
             raise PurchaseValidationError('Some selected servers are not available', code='invalid_servers')
 
-        total_without_promo, details = await self._calculate_base_total(
-            db,
-            context.user,
-            selection,
-            server_ids,
-        )
+        details = PricingEngine.classic_pricing_to_purchase_details(pricing)
 
-        base_original_total = (
-            details['base_price_original']
-            + details['traffic_price_per_month'] * months
-            + details['servers_price_per_month'] * months
-            + details['devices_price_per_month'] * months
-        )
-
-        final_total, promo_discount_value, promo_percent = _apply_promo_offer_discount(
-            context.user, total_without_promo
-        )
-
-        discounted_total = total_without_promo
+        base_original_total = pricing.original_total
+        discounted_total = pricing.final_total + pricing.promo_offer_discount  # subtotal before offer
+        promo_discount_value = pricing.promo_offer_discount
+        promo_percent = pricing.breakdown.get('offer_discount_pct', 0)
 
         is_valid = validate_pricing_calculation(
             details.get('base_price', 0),
@@ -755,30 +740,11 @@ class MiniAppSubscriptionPurchaseService:
             discounted_total=discounted_total,
             promo_discount_value=promo_discount_value,
             promo_discount_percent=promo_percent,
-            final_total=final_total,
+            final_total=pricing.final_total,
             months=months,
             details=details,
         )
 
-    async def _calculate_base_total(
-        self,
-        db: AsyncSession,
-        user: User,
-        selection: PurchaseSelection,
-        server_ids: list[int],
-    ) -> tuple[int, dict[str, Any]]:
-        from app.database.crud.subscription import calculate_subscription_total_cost
-
-        total_cost, details = await calculate_subscription_total_cost(
-            db,
-            selection.period.days,
-            selection.traffic_value,
-            server_ids,
-            selection.devices,
-            user=user,
-        )
-        return total_cost, details
-
     def build_preview_payload(
         self,
         context: PurchaseOptionsContext,

app/services/subscription_service.py

@@ -10,12 +10,8 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from app.config import settings
 from app.database.crud.server_squad import get_all_server_squads
 from app.database.crud.user import get_user_by_id
-from app.database.models import PromoGroup, Subscription, SubscriptionStatus, User
+from app.database.models import Subscription, SubscriptionStatus, User
 from app.external.remnawave_api import RemnaWaveAPI, RemnaWaveAPIError, RemnaWaveUser, TrafficLimitStrategy, UserStatus
-from app.utils.pricing_utils import (
-    calculate_months_from_days,
-    resolve_discount_percent,
-)
 from app.utils.subscription_utils import (
     resolve_hwid_device_limit_for_payload,
 )
@@ -773,120 +769,6 @@ class SubscriptionService:
             default_prices = [0] * len(country_uuids)
             return sum(default_prices), default_prices
 
-    async def calculate_subscription_price_with_months(
-        self,
-        period_days: int,
-        traffic_gb: int,
-        server_squad_ids: list[int],
-        devices: int,
-        db: AsyncSession,
-        *,
-        user: User | None = None,
-        promo_group: PromoGroup | None = None,
-    ) -> tuple[int, list[int]]:
-        from app.config import PERIOD_PRICES
-        from app.database.crud.server_squad import get_server_squad_by_id
-
-        if settings.MAX_DEVICES_LIMIT > 0 and devices > settings.MAX_DEVICES_LIMIT:
-            raise ValueError(f'Превышен максимальный лимит устройств: {settings.MAX_DEVICES_LIMIT}')
-
-        months_in_period = calculate_months_from_days(period_days)
-
-        base_price_original = PERIOD_PRICES.get(period_days, 0)
-        period_discount_percent = resolve_discount_percent(
-            user,
-            promo_group,
-            'period',
-            period_days=period_days,
-        )
-        base_discount_total = base_price_original * period_discount_percent // 100
-        base_price = base_price_original - base_discount_total
-
-        promo_group = promo_group or (user.get_primary_promo_group() if user else None)
-
-        traffic_price_per_month = settings.get_traffic_price(traffic_gb)
-        traffic_discount_percent = resolve_discount_percent(
-            user,
-            promo_group,
-            'traffic',
-            period_days=period_days,
-        )
-        traffic_discount_per_month = traffic_price_per_month * traffic_discount_percent // 100
-        discounted_traffic_per_month = traffic_price_per_month - traffic_discount_per_month
-        total_traffic_price = discounted_traffic_per_month * months_in_period
-
-        server_prices = []
-        total_servers_price = 0
-        servers_discount_percent = resolve_discount_percent(
-            user,
-            promo_group,
-            'servers',
-            period_days=period_days,
-        )
-
-        for server_id in server_squad_ids:
-            server = await get_server_squad_by_id(db, server_id)
-            if server and server.is_available and not server.is_full:
-                server_price_per_month = server.price_kopeks
-                server_discount_per_month = server_price_per_month * servers_discount_percent // 100
-                discounted_server_per_month = server_price_per_month - server_discount_per_month
-                server_price_total = discounted_server_per_month * months_in_period
-                server_prices.append(server_price_total)
-                total_servers_price += server_price_total
-                log_message = f'Сервер {server.display_name}: {server_price_per_month / 100}₽/мес x {months_in_period} мес = {server_price_total / 100}₽'
-                if server_discount_per_month > 0:
-                    log_message += (
-                        f' (скидка {servers_discount_percent}%: -{server_discount_per_month * months_in_period / 100}₽)'
-                    )
-                logger.debug(log_message)
-            else:
-                server_prices.append(0)
-                logger.warning('Сервер ID недоступен', server_id=server_id)
-
-        additional_devices = max(0, devices - settings.DEFAULT_DEVICE_LIMIT)
-        devices_price_per_month = additional_devices * settings.PRICE_PER_DEVICE
-        devices_discount_percent = resolve_discount_percent(
-            user,
-            promo_group,
-            'devices',
-            period_days=period_days,
-        )
-        devices_discount_per_month = devices_price_per_month * devices_discount_percent // 100
-        discounted_devices_per_month = devices_price_per_month - devices_discount_per_month
-        total_devices_price = discounted_devices_per_month * months_in_period
-
-        total_price = base_price + total_traffic_price + total_servers_price + total_devices_price
-
-        logger.debug(
-            'Расчет стоимости новой подписки на дней ( мес)', period_days=period_days, months_in_period=months_in_period
-        )
-        base_log = f'   Период {period_days} дней: {base_price_original / 100}₽'
-        if base_discount_total > 0:
-            base_log += f' → {base_price / 100}₽ (скидка {period_discount_percent}%: -{base_discount_total / 100}₽)'
-        logger.debug(base_log)
-        if total_traffic_price > 0:
-            message = f'   Трафик {traffic_gb} ГБ: {traffic_price_per_month / 100}₽/мес x {months_in_period} = {total_traffic_price / 100}₽'
-            if traffic_discount_per_month > 0:
-                message += (
-                    f' (скидка {traffic_discount_percent}%: -{traffic_discount_per_month * months_in_period / 100}₽)'
-                )
-            logger.debug(message)
-        if total_servers_price > 0:
-            message = f'   Серверы ({len(server_squad_ids)}): {total_servers_price / 100}₽'
-            if servers_discount_percent > 0:
-                message += f' (скидка {servers_discount_percent}% применяется ко всем серверам)'
-            logger.debug(message)
-        if total_devices_price > 0:
-            message = f'   Устройства ({additional_devices}): {devices_price_per_month / 100}₽/мес x {months_in_period} = {total_devices_price / 100}₽'
-            if devices_discount_per_month > 0:
-                message += (
-                    f' (скидка {devices_discount_percent}%: -{devices_discount_per_month * months_in_period / 100}₽)'
-                )
-            logger.debug(message)
-        logger.debug('ИТОГО: ₽', total_price=total_price / 100)
-
-        return total_price, server_prices
-
     def _gb_to_bytes(self, gb: int | None) -> int:
         if not gb:  # None or 0
             return 0

app/services/yookassa_service.py

@@ -133,9 +133,10 @@ class YooKassaService:
             )
 
             loop = asyncio.get_running_loop()
-            response = await loop.run_in_executor(
-                None, lambda: YooKassaPayment.create(payment_request, idempotence_key)
-            )
+            async with asyncio.timeout(30):
+                response = await loop.run_in_executor(
+                    None, lambda: YooKassaPayment.create(payment_request, idempotence_key)
+                )
 
             logger.info(
                 'Ответ YooKassa Payment.create: ID=, Status=, Paid',
@@ -241,9 +242,10 @@ class YooKassaService:
             )
 
             loop = asyncio.get_running_loop()
-            response = await loop.run_in_executor(
-                None, lambda: YooKassaPayment.create(payment_request, idempotence_key)
-            )
+            async with asyncio.timeout(30):
+                response = await loop.run_in_executor(
+                    None, lambda: YooKassaPayment.create(payment_request, idempotence_key)
+                )
 
             logger.info(
                 'Ответ YooKassa Payment.create (СБП, redirect): ID=, Status=, Paid',
@@ -288,7 +290,10 @@ class YooKassaService:
             logger.info('Получение информации о платеже YooKassa ID', payment_id_in_yookassa=payment_id_in_yookassa)
 
             loop = asyncio.get_running_loop()
-            payment_info_yk = await loop.run_in_executor(None, lambda: YooKassaPayment.find_one(payment_id_in_yookassa))
+            async with asyncio.timeout(30):
+                payment_info_yk = await loop.run_in_executor(
+                    None, lambda: YooKassaPayment.find_one(payment_id_in_yookassa)
+                )
 
             if payment_info_yk:
                 logger.info(
@@ -415,9 +420,10 @@ class YooKassaService:
             )
 
             loop = asyncio.get_running_loop()
-            response = await loop.run_in_executor(
-                None, lambda: YooKassaPayment.create(payment_request, idempotence_key)
-            )
+            async with asyncio.timeout(30):
+                response = await loop.run_in_executor(
+                    None, lambda: YooKassaPayment.create(payment_request, idempotence_key)
+                )
 
             logger.info(
                 'Ответ YooKassa автоплатёж',

app/utils/price_display.py

@@ -76,12 +76,10 @@ def calculate_user_price(user: User | None, base_price: int, period_days: int, c
 
         promo_offer_discount = get_user_active_promo_discount_percent(user)
 
-    # Apply both discounts sequentially (same as cabinet)
-    final_price = base_price
-    if group_discount > 0:
-        final_price = final_price - (final_price * group_discount) // 100
-    if promo_offer_discount > 0:
-        final_price = final_price - (final_price * promo_offer_discount) // 100
+    # Apply both discounts sequentially via PricingEngine
+    from app.services.pricing_engine import PricingEngine
+
+    final_price, _, _ = PricingEngine.apply_stacked_discounts(base_price, group_discount, promo_offer_discount)
 
     # Effective combined discount percent
     if final_price < base_price:

app/utils/pricing_utils.py

@@ -10,6 +10,7 @@ from app.config import settings
 
 if TYPE_CHECKING:  # pragma: no cover
     from app.database.models import PromoGroup, User
+    from app.services.pricing_engine import RenewalPricing
 
 logger = structlog.get_logger(__name__)
 
@@ -84,32 +85,45 @@ async def compute_simple_subscription_price(
     user: Optional['User'] = None,
     resolved_squad_uuids: Sequence[str] | None = None,
 ) -> tuple[int, dict[str, Any]]:
-    """Вычисляет стоимость простой подписки с учетом всех доплат и скидок."""
+    """Вычисляет стоимость простой подписки с учетом всех доплат и скидок.
+
+    Delegates to PricingEngine.calculate_classic_new_subscription_price()
+    and converts the RenewalPricing result to the legacy breakdown dict
+    expected by callers.
+    """
+    from app.services.pricing_engine import PricingEngine
 
     period_days = int(params.get('period_days', 30) or 30)
-    attr_name = f'PRICE_{period_days}_DAYS'
-    base_price_original = getattr(settings, attr_name, settings.BASE_SUBSCRIPTION_PRICE)
 
     traffic_limit_raw = params.get('traffic_limit_gb')
     try:
-        traffic_limit = int(traffic_limit_raw) if traffic_limit_raw is not None else None
+        traffic_limit_gb = int(traffic_limit_raw) if traffic_limit_raw is not None else 0
     except (TypeError, ValueError):  # pragma: no cover - defensive conversion
-        traffic_limit = None
-
-    if traffic_limit is None or traffic_limit <= 0:
-        # Default simple subscriptions already include unlimited traffic.
-        traffic_price_original = 0
-    else:
-        traffic_price_original = settings.get_traffic_price(traffic_limit)
+        traffic_limit_gb = 0
+    # Treat None / non-positive as unlimited (0 GB → price = 0 in PricingEngine)
+    traffic_limit_gb = max(traffic_limit_gb, 0)
 
     device_limit_raw = params.get('device_limit', settings.DEFAULT_DEVICE_LIMIT)
     try:
         device_limit = int(device_limit_raw)
     except (TypeError, ValueError):  # pragma: no cover - defensive conversion
         device_limit = settings.DEFAULT_DEVICE_LIMIT
-    additional_devices = max(0, device_limit - settings.DEFAULT_DEVICE_LIMIT)
-    devices_price_original = additional_devices * settings.PRICE_PER_DEVICE
 
+    # --- Resolve squad UUIDs from explicit arg or params ---
+    resolved_uuids: list[str] = []
+    if resolved_squad_uuids:
+        resolved_uuids.extend([uuid for uuid in resolved_squad_uuids if uuid])
+    else:
+        raw_squad = params.get('squad_uuid')
+        if isinstance(raw_squad, (list, tuple, set)):
+            resolved_uuids.extend([str(uuid) for uuid in raw_squad if uuid])
+        elif raw_squad:
+            resolved_uuids.append(str(raw_squad))
+
+    # --- Resolve promo_group from params (backward compat) ---
+    # Callers may pass promo_group or promo_group_id via params dict.
+    # PricingEngine resolves promo_group from user internally, so we only
+    # need this for the applied_promo_group_id field in the breakdown.
     promo_group: PromoGroup | None = params.get('promo_group')
 
     if promo_group is None:
@@ -122,131 +136,103 @@ async def compute_simple_subscription_price(
     if promo_group is None and user is not None:
         promo_group = user.get_primary_promo_group()
 
-    period_discount_percent = resolve_discount_percent(
-        user,
-        promo_group,
-        'period',
-        period_days=period_days,
-    )
-    base_discount = base_price_original * period_discount_percent // 100
-
-    traffic_discount_percent = resolve_discount_percent(
-        user,
-        promo_group,
-        'traffic',
-        period_days=period_days,
-    )
-    traffic_discount = traffic_price_original * traffic_discount_percent // 100
-
-    devices_discount_percent = resolve_discount_percent(
-        user,
-        promo_group,
-        'devices',
-        period_days=period_days,
-    )
-    devices_discount = devices_price_original * devices_discount_percent // 100
-
-    servers_discount_percent = resolve_discount_percent(
-        user,
-        promo_group,
-        'servers',
-        period_days=period_days,
+    # --- Delegate to PricingEngine ---
+    engine = PricingEngine()
+    pricing = await engine.calculate_classic_new_subscription_price(
+        db,
+        period_days,
+        resolved_uuids,
+        traffic_limit_gb,
+        device_limit,
+        user=user,
     )
 
-    resolved_uuids: list[str] = []
-    if resolved_squad_uuids:
-        resolved_uuids.extend([uuid for uuid in resolved_squad_uuids if uuid])
-    else:
-        raw_squad = params.get('squad_uuid')
-        if isinstance(raw_squad, (list, tuple, set)):
-            resolved_uuids.extend([str(uuid) for uuid in raw_squad if uuid])
-        elif raw_squad:
-            resolved_uuids.append(str(raw_squad))
+    # --- Build legacy breakdown dict from RenewalPricing + ClassicBreakdown ---
+    breakdown = _build_simple_subscription_breakdown(pricing, resolved_uuids, promo_group)
 
-    from app.database.crud.server_squad import get_server_squads_by_uuids
+    return pricing.final_total, breakdown
 
-    server_breakdown: list[dict[str, Any]] = []
-    servers_price_original = 0
-    servers_discount_total = 0
 
-    if resolved_uuids:
-        servers = await get_server_squads_by_uuids(db, resolved_uuids)
-        server_map = {s.squad_uuid: s for s in servers}
-    else:
-        server_map = {}
+def _build_simple_subscription_breakdown(
+    pricing: 'RenewalPricing',
+    resolved_uuids: list[str],
+    promo_group: Optional['PromoGroup'],
+) -> dict[str, Any]:
+    """Convert PricingEngine's RenewalPricing to the legacy breakdown dict.
 
-    for squad_uuid in resolved_uuids:
-        server = server_map.get(squad_uuid)
-        if not server:
-            logger.warning('SIMPLE_SUBSCRIPTION_PRICE_SERVER_NOT_FOUND | squad', squad_uuid=squad_uuid)
-            server_breakdown.append(
-                {
-                    'uuid': squad_uuid,
-                    'name': None,
-                    'available': False,
-                    'original_price': 0,
-                    'discount': 0,
-                    'final_price': 0,
-                }
-            )
-            continue
+    Preserves all keys that callers depend on:
+    base_price, base_discount, traffic_price, traffic_discount,
+    devices_price, devices_discount, servers_price, servers_discount,
+    servers_final, server_details, total_before_discount, total_discount,
+    resolved_squad_uuids, applied_promo_group_id, *_discount_percent.
+    """
+    from app.services.pricing_engine import PricingEngine
 
-        if not server.is_available or server.is_full:
-            logger.warning(
-                'SIMPLE_SUBSCRIPTION_PRICE_SERVER_UNAVAILABLE | squad= | available= | full',
-                squad_uuid=squad_uuid,
-                is_available=server.is_available,
-                is_full=server.is_full,
-            )
-            server_breakdown.append(
-                {
-                    'uuid': squad_uuid,
-                    'name': server.display_name,
-                    'available': False,
-                    'original_price': 0,
-                    'discount': 0,
-                    'final_price': 0,
-                }
-            )
-            continue
+    bd = pricing.breakdown
+    months = bd.get('months_in_period', 1) or 1
+    group_pct: dict[str, int] = bd.get('group_discount_pct', {})
 
-        original_price = server.price_kopeks
-        discount_value = original_price * servers_discount_percent // 100
-        final_price = original_price - discount_value
+    # Original (pre-discount) prices from ClassicBreakdown
+    base_price_original: int = bd.get('base_price_original', 0)
+    traffic_price_per_month: int = bd.get('traffic_price_per_month', 0)
+    servers_price_per_month: int = bd.get('servers_price_per_month', 0)
+    devices_price_per_month: int = bd.get('devices_price_per_month', 0)
 
-        servers_price_original += original_price
-        servers_discount_total += discount_value
+    # Per-category discount percents
+    period_discount_percent: int = group_pct.get('period', 0)
+    traffic_discount_percent: int = group_pct.get('traffic', 0)
+    servers_discount_percent: int = group_pct.get('servers', 0)
+    devices_discount_percent: int = group_pct.get('devices', 0)
 
-        server_breakdown.append(
+    # Total original prices (traffic/servers/devices are monthly × months)
+    traffic_price_total = traffic_price_per_month * months
+    servers_price_total = servers_price_per_month * months
+    devices_price_total = devices_price_per_month * months
+
+    # Discount values
+    base_discount = base_price_original - pricing.base_price
+    traffic_discount = traffic_price_total - pricing.traffic_price
+    servers_discount = servers_price_total - pricing.servers_price
+    devices_discount = devices_price_total - pricing.devices_price
+
+    total_before_discount = base_price_original + traffic_price_total + servers_price_total + devices_price_total
+    # Group discounts only (promo_offer_discount is separate and already
+    # reflected in final_total but NOT in per-category values above).
+    total_discount = base_discount + traffic_discount + servers_discount + devices_discount
+
+    # Build server_details in legacy format from PricingEngine's server list
+    server_details: list[dict[str, Any]] = []
+    servers_final = 0
+    for srv in bd.get('servers', []):
+        original_price = srv.get('price', 0)
+        status = srv.get('status', 'available')
+        is_available = status == 'available'
+        final_price = PricingEngine.apply_discount(original_price, servers_discount_percent) if is_available else 0
+        discount_value = original_price - final_price if is_available else 0
+        servers_final += final_price
+
+        server_details.append(
             {
-                'uuid': squad_uuid,
-                'name': server.display_name,
-                'available': True,
-                'original_price': original_price,
+                'uuid': srv.get('uuid', ''),
+                'name': None,  # PricingEngine._calculate_servers_price doesn't return display_name
+                'available': is_available,
+                'original_price': original_price if is_available else 0,
                 'discount': discount_value,
                 'final_price': final_price,
             }
         )
 
-    total_before_discount = (
-        base_price_original + traffic_price_original + devices_price_original + servers_price_original
-    )
-
-    total_discount = base_discount + traffic_discount + devices_discount + servers_discount_total
-
-    total_price = max(0, total_before_discount - total_discount)
-
-    breakdown = {
+    return {
         'base_price': base_price_original,
         'base_discount': base_discount,
-        'traffic_price': traffic_price_original,
+        'traffic_price': traffic_price_total,
         'traffic_discount': traffic_discount,
-        'devices_price': devices_price_original,
+        'devices_price': devices_price_total,
         'devices_discount': devices_discount,
-        'servers_price': servers_price_original,
-        'servers_discount': servers_discount_total,
-        'servers_final': sum(item['final_price'] for item in server_breakdown),
-        'server_details': server_breakdown,
+        'servers_price': servers_price_total,
+        'servers_discount': servers_discount,
+        'servers_final': servers_final,
+        'server_details': server_details,
         'total_before_discount': total_before_discount,
         'total_discount': total_discount,
         'resolved_squad_uuids': resolved_uuids,
@@ -257,8 +243,6 @@ async def compute_simple_subscription_price(
         'servers_discount_percent': servers_discount_percent,
     }
 
-    return total_price, breakdown
-
 
 def _pluralize_days_ru(n: int) -> str:
     """Склонение слова 'день' по числу: 1 день, 2 дня, 5 дней."""

app/utils/promo_offer.py

@@ -35,6 +35,44 @@ def get_user_active_promo_discount_percent(user: User | None) -> int:
     return max(0, min(100, percent))
 
 
+async def consume_user_promo_offer(db: AsyncSession, user_id: int) -> bool:
+    """Consume the user's one-shot promo-offer discount (zeroes out the fields).
+
+    Used by external payment fulfillment handlers (Stars, YooKassa)
+    where subtract_user_balance (which normally consumes the offer) is not called.
+    Returns True if an offer was actually consumed.
+    """
+    from app.database.crud.promo_offer_log import log_promo_offer_action
+
+    result = await db.execute(select(User).where(User.id == user_id).with_for_update())
+    user = result.scalar_one_or_none()
+    if not user:
+        return False
+
+    current_percent = int(getattr(user, 'promo_offer_discount_percent', 0) or 0)
+    if current_percent <= 0:
+        return False
+
+    offer_id = getattr(user, 'promo_offer_discount_source', None)
+    user.promo_offer_discount_percent = 0
+    user.promo_offer_discount_source = None
+    user.promo_offer_discount_expires_at = None
+    await db.flush()
+
+    try:
+        await log_promo_offer_action(
+            db,
+            user_id=user_id,
+            offer_id=offer_id,
+            action='consumed_external_payment',
+            discount_percent=current_percent,
+        )
+    except Exception:
+        pass  # Non-critical logging
+
+    return True
+
+
 def _format_time_left(seconds_left: int, language: str) -> str:
     total_minutes = max(1, math.ceil(seconds_left / 60))
     days, remainder_minutes = divmod(total_minutes, 60 * 24)

app/webapi/routes/miniapp.py

@@ -58,6 +58,7 @@ from app.database.models import (
 from app.services.faq_service import FaqService
 from app.services.maintenance_service import maintenance_service
 from app.services.payment_service import PaymentService, get_wata_payment_by_link_id
+from app.services.pricing_engine import PricingEngine
 from app.services.privacy_policy_service import PrivacyPolicyService
 from app.services.promo_offer_service import promo_offer_service
 from app.services.promocode_service import PromoCodeService
@@ -210,12 +211,11 @@ _CRYPTOBOT_FALLBACK_RATE = 95.0
 
 
 def _get_tariff_monthly_price(tariff) -> int:
-    """Получает месячную цену тарифа (30 дней) с fallback на пропорциональный расчёт."""
+    """Получает месячную цену тарифа (30 дней) для отображения в UI."""
     price = tariff.get_price_for_period(30)
     if price is not None:
         return price
 
-    # Fallback: пропорционально пересчитываем из первого доступного периода
     periods = tariff.get_available_periods()
     if periods:
         first_period = periods[0]
@@ -3341,6 +3341,15 @@ async def get_subscription_details(
             is_daily_paused = getattr(subscription, 'is_daily_paused', False)
             daily_tariff_name = tariff.name
             daily_price_kopeks = getattr(tariff, 'daily_price_kopeks', 0)
+            # Применяем скидку промогруппы + promo-offer для отображения
+            if daily_price_kopeks > 0:
+                _promo_group = user.get_primary_promo_group() if hasattr(user, 'get_primary_promo_group') else None
+                _group_pct = _promo_group.get_discount_percent('period', 1) if _promo_group else 0
+                _offer_pct = get_user_active_promo_discount_percent(user) if user else 0
+                if _group_pct > 0 or _offer_pct > 0:
+                    daily_price_kopeks, _, _ = PricingEngine.apply_stacked_discounts(
+                        daily_price_kopeks, _group_pct, _offer_pct
+                    )
             daily_price_label = settings.format_price(daily_price_kopeks) + '/день' if daily_price_kopeks > 0 else None
             # Оставшееся время подписки (показываем даже при паузе)
             if subscription.end_date:
@@ -3510,21 +3519,10 @@ async def _get_current_tariff_model(db: AsyncSession, subscription, user=None) -
 
     servers_count = len(tariff.allowed_squads) if tariff.allowed_squads else 0
 
-    # Получаем скидку на трафик из промогруппы
-    traffic_discount_percent = 0
-    promo_group = (
-        (
-            user.get_primary_promo_group()
-            if hasattr(user, 'get_primary_promo_group')
-            else getattr(user, 'promo_group', None)
-        )
-        if user
-        else None
-    )
-    if promo_group:
-        apply_to_addons = getattr(promo_group, 'apply_discounts_to_addons', True)
-        if apply_to_addons:
-            traffic_discount_percent = max(0, min(100, int(getattr(promo_group, 'traffic_discount_percent', 0) or 0)))
+    # Скидка на трафик через PricingEngine
+    from app.services.pricing_engine import PricingEngine, pricing_engine
+
+    promo_group = PricingEngine.resolve_promo_group(user) if user else None
 
     # Лимит докупки трафика
     max_topup_traffic_gb = getattr(tariff, 'max_topup_traffic_gb', 0) or 0
@@ -3547,9 +3545,12 @@ async def _get_current_tariff_model(db: AsyncSession, subscription, user=None) -
                 continue
 
             base_price = packages[gb]
-            # Применяем скидку
-            if traffic_discount_percent > 0:
-                discounted_price = int(base_price * (100 - traffic_discount_percent) / 100)
+            # Применяем скидку через PricingEngine
+            discounted_price, _discount_val, traffic_discount_pct = pricing_engine.calculate_traffic_discount(
+                base_price,
+                user,
+            )
+            if traffic_discount_pct > 0:
                 traffic_topup_packages.append(
                     MiniAppTrafficTopupPackage(
                         gb=gb,
@@ -3557,7 +3558,7 @@ async def _get_current_tariff_model(db: AsyncSession, subscription, user=None) -
                         price_label=settings.format_price(discounted_price),
                         original_price_kopeks=base_price,
                         original_price_label=settings.format_price(base_price),
-                        discount_percent=traffic_discount_percent,
+                        discount_percent=traffic_discount_pct,
                     )
                 )
             else:
@@ -3577,15 +3578,9 @@ async def _get_current_tariff_model(db: AsyncSession, subscription, user=None) -
 
     # Применяем скидку промогруппы для 30-дневного периода
     if promo_group:
-        raw_discounts = getattr(promo_group, 'period_discounts', None) or {}
-        for k, v in raw_discounts.items():
-            try:
-                if int(k) == 30:
-                    discount = max(0, min(100, int(v)))
-                    monthly_price = int(monthly_price * (100 - discount) / 100)
-                    break
-            except (TypeError, ValueError):
-                pass
+        discount = promo_group.get_discount_percent('period', 30)
+        if discount > 0:
+            monthly_price = PricingEngine.apply_discount(monthly_price, discount)
 
     return MiniAppCurrentTariff(
         id=tariff.id,
@@ -4613,32 +4608,6 @@ async def _prepare_subscription_renewal_options(
     return periods, pricing_map, recommended_option[0].id
 
 
-def _get_addon_discount_percent_for_user(
-    user: User | None,
-    category: str,
-    period_days_hint: int | None = None,
-) -> int:
-    if user is None:
-        return 0
-
-    promo_group = getattr(user, 'promo_group', None)
-    if promo_group is None:
-        return 0
-
-    if not getattr(promo_group, 'apply_discounts_to_addons', True):
-        return 0
-
-    try:
-        percent = user.get_promo_discount(category, period_days_hint)
-    except AttributeError:
-        return 0
-
-    try:
-        return int(percent)
-    except (TypeError, ValueError):
-        return 0
-
-
 def _get_period_hint_from_subscription(
     subscription: Subscription | None,
 ) -> int | None:
@@ -4916,21 +4885,9 @@ async def _build_subscription_settings(
 ) -> MiniAppSubscriptionSettings:
     period_hint_days = _get_period_hint_from_subscription(subscription)
     months_remaining = max(1, math.ceil((period_hint_days or 0) / 30))
-    servers_discount = _get_addon_discount_percent_for_user(
-        user,
-        'servers',
-        period_hint_days,
-    )
-    traffic_discount = _get_addon_discount_percent_for_user(
-        user,
-        'traffic',
-        period_hint_days,
-    )
-    devices_discount = _get_addon_discount_percent_for_user(
-        user,
-        'devices',
-        period_hint_days,
-    )
+    servers_discount = PricingEngine.get_addon_discount_percent(user, 'servers', period_hint_days)
+    traffic_discount = PricingEngine.get_addon_discount_percent(user, 'traffic', period_hint_days)
+    devices_discount = PricingEngine.get_addon_discount_percent(user, 'devices', period_hint_days)
 
     current_servers, server_options, _ = await _prepare_server_catalog(
         db,
@@ -5193,6 +5150,10 @@ async def submit_subscription_renewal_endpoint(
                 detail={'code': 'period_unavailable', 'message': 'Selected renewal period is not available'},
             )
 
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     try:
         pricing_result = await pricing_engine.calculate_renewal_price(db, subscription, period_days, user=user)
     except HTTPException:
@@ -5450,6 +5411,10 @@ async def subscription_purchase_endpoint(
     db: AsyncSession = Depends(get_db_session),
 ) -> MiniAppSubscriptionPurchaseResponse:
     user = await _authorize_miniapp_user(payload.init_data, db)
+
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
     context = await purchase_service.build_options(db, user)
 
     selection_payload = _merge_purchase_selection_from_request(payload)
@@ -5593,12 +5558,13 @@ async def update_subscription_servers_endpoint(
             message='No changes',
         )
 
+    # Lock user BEFORE price computation to prevent TOCTOU on promo discount
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     period_hint_days = _get_period_hint_from_subscription(subscription)
-    servers_discount = _get_addon_discount_percent_for_user(
-        user,
-        'servers',
-        period_hint_days,
-    )
+    servers_discount = PricingEngine.get_addon_discount_percent(user, 'servers', period_hint_days)
 
     _, _, catalog = await _prepare_server_catalog(
         db,
@@ -5816,23 +5782,18 @@ async def update_subscription_traffic_endpoint(
 
     days_remaining = max(1, (subscription.end_date - datetime.now(UTC)).days)
     period_hint_days = days_remaining
-    traffic_discount = _get_addon_discount_percent_for_user(
-        user,
-        'traffic',
-        period_hint_days,
-    )
+
+    # Lock user BEFORE discount computation to prevent TOCTOU on promo group
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+    traffic_discount = PricingEngine.get_addon_discount_percent(user, 'traffic', period_hint_days)
 
     old_price_per_month = settings.get_traffic_price(subscription.traffic_limit_gb)
     new_price_per_month = settings.get_traffic_price(new_traffic)
 
-    discounted_old_per_month, _ = apply_percentage_discount(
-        old_price_per_month,
-        traffic_discount,
-    )
-    discounted_new_per_month, _ = apply_percentage_discount(
-        new_price_per_month,
-        traffic_discount,
-    )
+    discounted_old_per_month = PricingEngine.apply_discount(old_price_per_month, traffic_discount)
+    discounted_new_per_month = PricingEngine.apply_discount(new_price_per_month, traffic_discount)
 
     price_difference_per_month = discounted_new_per_month - discounted_old_per_month
     total_price_difference = 0
@@ -5998,16 +5959,15 @@ async def update_subscription_devices_endpoint(
         price_per_month = chargeable_diff * tariff_device_price
         days_remaining = max(1, (subscription.end_date - datetime.now(UTC)).days)
         period_hint_days = days_remaining
-        devices_discount = _get_addon_discount_percent_for_user(
-            user,
-            'devices',
-            period_hint_days,
-        )
 
-        discounted_per_month, _ = apply_percentage_discount(
-            price_per_month,
-            devices_discount,
-        )
+        # Lock user BEFORE price computation to prevent TOCTOU on promo discount
+        from app.database.crud.user import lock_user_for_pricing
+
+        user = await lock_user_for_pricing(db, user.id)
+
+        devices_discount = PricingEngine.get_addon_discount_percent(user, 'devices', period_hint_days)
+
+        discounted_per_month = PricingEngine.apply_discount(price_per_month, devices_discount)
         price_to_charge, charged_days = calculate_prorated_price(
             discounted_per_month,
             subscription.end_date,
@@ -6150,27 +6110,22 @@ async def _build_tariff_model(
                     )
                 )
 
-    # Получаем скидки промогруппы по периодам
-    period_discounts = {}
-    if promo_group:
-        raw_discounts = getattr(promo_group, 'period_discounts', None) or {}
-        for k, v in raw_discounts.items():
-            try:
-                period_discounts[int(k)] = max(0, min(100, int(v)))
-            except (TypeError, ValueError):
-                pass
-
     periods: list[MiniAppTariffPeriod] = []
     if tariff.period_prices:
         for period_str, original_price_kopeks in sorted(tariff.period_prices.items(), key=lambda x: int(x[0])):
             period_days = int(period_str)
 
-            # Применяем скидку промогруппы
-            discount_percent = period_discounts.get(period_days, 0)
-            if discount_percent > 0:
-                price_kopeks = int(original_price_kopeks * (100 - discount_percent) / 100)
+            # Применяем скидку промогруппы + promo-offer (stacked)
+            group_pct = promo_group.get_discount_percent('period', period_days) if promo_group else 0
+            offer_pct = get_user_active_promo_discount_percent(user) if user else 0
+            if group_pct > 0 or offer_pct > 0:
+                price_kopeks, _, _ = PricingEngine.apply_stacked_discounts(original_price_kopeks, group_pct, offer_pct)
+                # Комбинированный процент для отображения
+                remaining = (100 - group_pct) * (100 - offer_pct)
+                discount_percent = 100 - remaining // 100
             else:
                 price_kopeks = original_price_kopeks
+                discount_percent = 0
 
             months = max(1, period_days // 30)
             per_month = price_kopeks // months if months > 0 else price_kopeks
@@ -6197,31 +6152,31 @@ async def _build_tariff_model(
     is_switch_free = None
 
     if current_tariff and current_tariff.id != tariff.id:
-        current_is_daily = getattr(current_tariff, 'is_daily', False)
-        new_is_daily = getattr(tariff, 'is_daily', False)
-
-        if current_is_daily and not new_is_daily:
-            # Переключение С суточного НА периодный - полная оплата нового тарифа
-            # Берём минимальную цену из периодов нового тарифа
-            min_period_price = None
-            if periods:
-                min_period_price = min(p.price_kopeks for p in periods)
-            if min_period_price and min_period_price > 0:
-                switch_cost_kopeks = min_period_price
-                switch_cost_label = settings.format_price(min_period_price)
-                is_upgrade = True  # Показываем как платный переход
-                is_switch_free = False
-        elif remaining_days > 0:
-            # Обычный расчёт для периодных тарифов
-            cost, upgrade = _calculate_tariff_switch_cost(current_tariff, tariff, remaining_days, promo_group, user)
-            switch_cost_kopeks = cost
-            switch_cost_label = settings.format_price(cost) if cost > 0 else None
-            is_upgrade = upgrade
-            is_switch_free = cost == 0
+        # PricingEngine обрабатывает все случаи: periodic↔periodic, daily→periodic, periodic→daily
+        result = _calculate_tariff_switch(current_tariff, tariff, remaining_days, user=user)
+        switch_cost_kopeks = result.upgrade_cost
+        switch_cost_label = settings.format_price(result.upgrade_cost) if result.upgrade_cost > 0 else None
+        is_upgrade = result.is_upgrade
+        is_switch_free = result.upgrade_cost == 0
 
     # Суточный тариф
     is_daily = getattr(tariff, 'is_daily', False)
-    daily_price_kopeks = getattr(tariff, 'daily_price_kopeks', 0) if is_daily else 0
+    raw_daily_price_kopeks = getattr(tariff, 'daily_price_kopeks', 0) if is_daily else 0
+    daily_price_kopeks = raw_daily_price_kopeks
+
+    # Применяем скидку промогруппы + promo-offer для суточного тарифа (period_hint=1)
+    if is_daily and daily_price_kopeks > 0:
+        daily_group_pct = (
+            promo_group.get_discount_percent('period', 1)
+            if promo_group and hasattr(promo_group, 'get_discount_percent')
+            else 0
+        )
+        daily_offer_pct = get_user_active_promo_discount_percent(user) if user else 0
+        if daily_group_pct > 0 or daily_offer_pct > 0:
+            daily_price_kopeks, _, _ = PricingEngine.apply_stacked_discounts(
+                raw_daily_price_kopeks, daily_group_pct, daily_offer_pct
+            )
+
     daily_price_label = (
         settings.format_price(daily_price_kopeks) + '/день' if is_daily and daily_price_kopeks > 0 else None
     )
@@ -6250,26 +6205,31 @@ async def _build_tariff_model(
     )
 
 
-async def _build_current_tariff_model(db: AsyncSession, tariff, promo_group=None) -> MiniAppCurrentTariff:
+async def _build_current_tariff_model(db: AsyncSession, tariff, promo_group=None, user=None) -> MiniAppCurrentTariff:
     """Создаёт модель текущего тарифа."""
     servers_count = len(tariff.allowed_squads) if tariff.allowed_squads else 0
     monthly_price = _get_tariff_monthly_price(tariff)
 
-    # Применяем скидку промогруппы для 30-дневного периода
-    if promo_group:
-        raw_discounts = getattr(promo_group, 'period_discounts', None) or {}
-        for k, v in raw_discounts.items():
-            try:
-                if int(k) == 30:
-                    discount = max(0, min(100, int(v)))
-                    monthly_price = int(monthly_price * (100 - discount) / 100)
-                    break
-            except (TypeError, ValueError):
-                pass
+    # Применяем скидку промогруппы + promo-offer для 30-дневного периода
+    group_pct = promo_group.get_discount_percent('period', 30) if promo_group else 0
+    offer_pct = get_user_active_promo_discount_percent(user) if user else 0
+    if group_pct > 0 or offer_pct > 0:
+        monthly_price, _, _ = PricingEngine.apply_stacked_discounts(monthly_price, group_pct, offer_pct)
 
     # Суточный тариф
     is_daily = getattr(tariff, 'is_daily', False)
-    daily_price_kopeks = getattr(tariff, 'daily_price_kopeks', 0) if is_daily else 0
+    raw_daily_price_kopeks = getattr(tariff, 'daily_price_kopeks', 0) if is_daily else 0
+    daily_price_kopeks = raw_daily_price_kopeks
+
+    # Применяем скидку промогруппы + promo-offer для суточного тарифа (period_hint=1)
+    if is_daily and daily_price_kopeks > 0:
+        daily_group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+        daily_offer_pct = get_user_active_promo_discount_percent(user) if user else 0
+        if daily_group_pct > 0 or daily_offer_pct > 0:
+            daily_price_kopeks, _, _ = PricingEngine.apply_stacked_discounts(
+                raw_daily_price_kopeks, daily_group_pct, daily_offer_pct
+            )
+
     daily_price_label = (
         settings.format_price(daily_price_kopeks) + '/день' if is_daily and daily_price_kopeks > 0 else None
     )
@@ -6310,11 +6270,9 @@ async def get_tariffs_endpoint(
         )
 
     # Получаем промогруппу пользователя (с приоритетом)
-    promo_group = (
-        user.get_primary_promo_group()
-        if hasattr(user, 'get_primary_promo_group')
-        else getattr(user, 'promo_group', None)
-    )
+    from app.services.pricing_engine import PricingEngine
+
+    promo_group = PricingEngine.resolve_promo_group(user)
     promo_group_id = promo_group.id if promo_group else None
 
     # Получаем тарифы, доступные пользователю
@@ -6335,7 +6293,7 @@ async def get_tariffs_endpoint(
     if current_tariff_id:
         current_tariff = await get_tariff_by_id(db, current_tariff_id)
         if current_tariff:
-            current_tariff_model = await _build_current_tariff_model(db, current_tariff, promo_group)
+            current_tariff_model = await _build_current_tariff_model(db, current_tariff, promo_group, user=user)
 
     # Формируем список тарифов
     tariff_models: list[MiniAppTariff] = []
@@ -6398,12 +6356,14 @@ async def purchase_tariff_endpoint(
             },
         )
 
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+    from app.services.pricing_engine import PricingEngine, pricing_engine
+
+    user = await lock_user_for_pricing(db, user.id)
+
     # Проверяем доступность тарифа для пользователя
-    promo_group = (
-        user.get_primary_promo_group()
-        if hasattr(user, 'get_primary_promo_group')
-        else getattr(user, 'promo_group', None)
-    )
+    promo_group = PricingEngine.resolve_promo_group(user)
     promo_group_id = promo_group.id if promo_group else None
     if not tariff.is_available_for_promo_group(promo_group_id):
         raise HTTPException(
@@ -6414,67 +6374,28 @@ async def purchase_tariff_endpoint(
             },
         )
 
-    # Получаем цену
+    # For daily tariffs, force period_days=1 (protect against client manipulation)
     is_daily_tariff = getattr(tariff, 'is_daily', False)
     if is_daily_tariff:
-        # Для суточного тарифа принудительно 1 день (защита от манипуляций с period_days)
         payload.period_days = 1
-        # Для суточного тарифа берём daily_price_kopeks (первый день)
-        base_price_kopeks = getattr(tariff, 'daily_price_kopeks', 0)
-        if base_price_kopeks <= 0:
-            raise HTTPException(
-                status_code=status.HTTP_400_BAD_REQUEST,
-                detail={
-                    'code': 'invalid_daily_price',
-                    'message': 'Daily tariff has no price configured',
-                },
-            )
-    else:
-        # Для обычного тарифа получаем цену за выбранный период
-        base_price_kopeks = tariff.get_price_for_period(payload.period_days)
-        if base_price_kopeks is None:
-            raise HTTPException(
-                status_code=status.HTTP_400_BAD_REQUEST,
-                detail={
-                    'code': 'invalid_period',
-                    'message': 'Invalid period for this tariff',
-                },
-            )
 
-    # Add extra device cost if user renews same tariff with purchased extra devices
+    # Calculate price via PricingEngine (single source of truth)
     subscription = getattr(user, 'subscription', None)
-    if not is_daily_tariff and subscription and subscription.tariff_id == tariff.id:
-        device_price_per_unit = (
-            tariff.device_price_kopeks if tariff.device_price_kopeks is not None else settings.PRICE_PER_DEVICE
-        )
-        extra_devices = max(0, (subscription.device_limit or 0) - (tariff.device_limit or 0))
-        base_price_kopeks += extra_devices * device_price_per_unit
+    device_limit = None
+    if subscription and subscription.tariff_id == tariff.id:
+        device_limit = subscription.device_limit
 
-    # Применяем скидку промогруппы (только для обычных тарифов, не для суточных)
-    price_kopeks = base_price_kopeks
-    discount_percent = 0
-    if not is_daily_tariff and promo_group:
-        raw_discounts = getattr(promo_group, 'period_discounts', None) or {}
-        for k, v in raw_discounts.items():
-            try:
-                if int(k) == payload.period_days:
-                    discount_percent = max(0, min(100, int(v)))
-                    break
-            except (TypeError, ValueError):
-                pass
-        if discount_percent > 0:
-            from app.services.pricing_engine import PricingEngine
-
-            price_kopeks = PricingEngine.apply_discount(base_price_kopeks, discount_percent)
-
-    # Apply personal promo_offer discount on top of group discount
-    consume_promo_offer = False
-    if not is_daily_tariff:
-        promo_offer_pct = get_user_active_promo_discount_percent(user)
-        if promo_offer_pct > 0:
-            offer_discount_value = price_kopeks * promo_offer_pct // 100
-            price_kopeks = price_kopeks - offer_discount_value
-            consume_promo_offer = True
+    result = await pricing_engine.calculate_tariff_purchase_price(
+        tariff,
+        payload.period_days,
+        device_limit=device_limit,
+        user=user,
+    )
+    price_kopeks = result.final_total
+    consume_promo_offer = result.promo_offer_discount > 0
+    bd = result.breakdown
+    group_pcts = bd.get('group_discount_pct', {})
+    discount_percent = group_pcts.get('period', 0)
 
     # Проверяем баланс
     if user.balance_kopeks < price_kopeks:
@@ -6615,70 +6536,28 @@ async def purchase_tariff_endpoint(
     )
 
 
-def _get_user_period_discount(user, period_days: int) -> int:
-    """Получает скидку пользователя на период (унифицировано с ботом)."""
-    promo_group = getattr(user, 'promo_group', None) if user else None
-
-    if promo_group:
-        discount = promo_group.get_discount_percent('period', period_days)
-        if discount > 0:
-            return discount
-
-    personal_discount = get_user_active_promo_discount_percent(user) if user else 0
-    return personal_discount
-
-
-def _apply_promo_discount(price: int, discount_percent: int) -> int:
-    """Применяет скидку к цене (через PricingEngine для единообразия)."""
-    from app.services.pricing_engine import PricingEngine
-
-    return PricingEngine.apply_discount(price, discount_percent)
-
-
-def _calculate_tariff_switch_cost(
+def _calculate_tariff_switch(
     current_tariff,
     new_tariff,
     remaining_days: int,
-    promo_group=None,
     user=None,
-) -> tuple[int, bool]:
-    """
-    Рассчитывает стоимость переключения тарифа.
-    Логика унифицирована с ботом (tariff_purchase.py).
-
-    Формула: (new_monthly - current_monthly) * remaining_days / 30
-    Скидка применяется к обоим тарифам одинаково.
+):
+    """Рассчитывает стоимость переключения тарифа.
 
+    Делегирует расчёт в PricingEngine.calculate_tariff_switch_cost().
+    PricingEngine автоматически определяет тип переключения
+    (periodic↔periodic, daily→periodic, periodic→daily).
     Returns:
-        (cost_kopeks, is_upgrade) - стоимость доплаты и флаг апгрейда
+        TariffSwitchResult
     """
-    current_monthly = _get_tariff_monthly_price(current_tariff)
-    new_monthly = _get_tariff_monthly_price(new_tariff)
+    from app.services.pricing_engine import pricing_engine
 
-    discount_percent = _get_user_period_discount(user, 30) if user else 0
-
-    # Fallback на promo_group.period_discounts если user не передан
-    if discount_percent == 0 and promo_group:
-        raw_discounts = getattr(promo_group, 'period_discounts', None) or {}
-        for k, v in raw_discounts.items():
-            try:
-                if int(k) == 30:
-                    discount_percent = max(0, min(100, int(v)))
-                    break
-            except (TypeError, ValueError):
-                pass
-
-    if discount_percent > 0:
-        current_monthly = _apply_promo_discount(current_monthly, discount_percent)
-        new_monthly = _apply_promo_discount(new_monthly, discount_percent)
-
-    price_diff = new_monthly - current_monthly
-
-    if price_diff <= 0:
-        return 0, False
-
-    upgrade_cost = int(price_diff * remaining_days / 30)
-    return upgrade_cost, True
+    return pricing_engine.calculate_tariff_switch_cost(
+        current_tariff,
+        new_tariff,
+        remaining_days,
+        user=user,
+    )
 
 
 @router.post('/subscription/tariff/switch/preview')
@@ -6725,11 +6604,9 @@ async def preview_tariff_switch_endpoint(
         )
 
     # Проверяем доступность тарифа для пользователя
-    promo_group = (
-        user.get_primary_promo_group()
-        if hasattr(user, 'get_primary_promo_group')
-        else getattr(user, 'promo_group', None)
-    )
+    from app.services.pricing_engine import PricingEngine
+
+    promo_group = PricingEngine.resolve_promo_group(user)
     promo_group_id = promo_group.id if promo_group else None
     if not new_tariff.is_available_for_promo_group(promo_group_id):
         raise HTTPException(
@@ -6743,22 +6620,10 @@ async def preview_tariff_switch_endpoint(
         delta = subscription.end_date - datetime.now(UTC)
         remaining_days = max(0, delta.days)
 
-    # Рассчитываем стоимость переключения
-    current_is_daily = getattr(current_tariff, 'is_daily', False) if current_tariff else False
-    new_is_daily = getattr(new_tariff, 'is_daily', False)
-
-    if current_is_daily and not new_is_daily:
-        # Переключение С суточного НА периодный - полная оплата нового тарифа
-        # Берём минимальную цену из периодов нового тарифа
-        min_period_price = 0
-        if new_tariff.period_prices:
-            min_period_price = min(new_tariff.period_prices.values())
-        upgrade_cost = min_period_price
-        is_upgrade = min_period_price > 0
-    else:
-        upgrade_cost, is_upgrade = _calculate_tariff_switch_cost(
-            current_tariff, new_tariff, remaining_days, promo_group, user
-        )
+    # Рассчитываем стоимость переключения (PricingEngine обрабатывает все случаи: periodic↔periodic, daily↔periodic)
+    switch_result = _calculate_tariff_switch(current_tariff, new_tariff, remaining_days, user=user)
+    upgrade_cost = switch_result.upgrade_cost
+    is_upgrade = switch_result.is_upgrade
 
     balance = user.balance_kopeks or 0
     has_enough = balance >= upgrade_cost
@@ -6836,11 +6701,9 @@ async def switch_tariff_endpoint(
         )
 
     # Проверяем доступность тарифа
-    promo_group = (
-        user.get_primary_promo_group()
-        if hasattr(user, 'get_primary_promo_group')
-        else getattr(user, 'promo_group', None)
-    )
+    from app.services.pricing_engine import PricingEngine
+
+    promo_group = PricingEngine.resolve_promo_group(user)
     promo_group_id = promo_group.id if promo_group else None
     if not new_tariff.is_available_for_promo_group(promo_group_id):
         raise HTTPException(
@@ -6848,35 +6711,26 @@ async def switch_tariff_endpoint(
             detail={'code': 'tariff_not_available', 'message': 'Tariff not available'},
         )
 
+    # Lock user BEFORE price computation to prevent TOCTOU on promo offer
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
     # Рассчитываем оставшиеся дни
     remaining_days = 0
     if subscription.end_date and subscription.end_date > datetime.now(UTC):
         delta = subscription.end_date - datetime.now(UTC)
         remaining_days = max(0, delta.days)
 
-    # Рассчитываем стоимость
+    # Рассчитываем стоимость (PricingEngine обрабатывает все случаи)
+    switch_result = _calculate_tariff_switch(current_tariff, new_tariff, remaining_days, user=user)
+    upgrade_cost = switch_result.upgrade_cost
+    new_period_days = switch_result.new_period_days
+
     current_is_daily = getattr(current_tariff, 'is_daily', False) if current_tariff else False
     new_is_daily = getattr(new_tariff, 'is_daily', False)
     switching_from_daily = current_is_daily and not new_is_daily
 
-    if switching_from_daily:
-        # Переключение С суточного НА периодный - полная оплата нового тарифа (минимальный период)
-        min_period_days = 30  # По умолчанию месяц
-        min_period_price = 0
-        if new_tariff.period_prices:
-            # Находим минимальный период и его цену
-            min_period_days = min(int(k) for k in new_tariff.period_prices.keys())
-            min_period_price = new_tariff.period_prices.get(str(min_period_days), 0)
-        upgrade_cost = min_period_price
-        is_upgrade = min_period_price > 0
-        # remaining_days для нового тарифа будет равен min_period_days после покупки
-        new_period_days = min_period_days
-    else:
-        upgrade_cost, is_upgrade = _calculate_tariff_switch_cost(
-            current_tariff, new_tariff, remaining_days, promo_group, user
-        )
-        new_period_days = 0  # Не меняем дату окончания
-
     # Списываем доплату если апгрейд
     if upgrade_cost > 0:
         if user.balance_kopeks < upgrade_cost:
@@ -6899,6 +6753,7 @@ async def switch_tariff_endpoint(
             user,
             upgrade_cost,
             description,
+            consume_promo_offer=switch_result.offer_discount_pct > 0,
             mark_as_paid_subscription=True,
             commit=False,
         )
@@ -7143,20 +6998,18 @@ async def purchase_traffic_topup_endpoint(
 
     base_price_kopeks = packages[payload.gb]
 
-    # Применяем скидку промогруппы на трафик
-    traffic_discount_percent = 0
-    promo_group = (
-        user.get_primary_promo_group()
-        if hasattr(user, 'get_primary_promo_group')
-        else getattr(user, 'promo_group', None)
-    )
-    if promo_group:
-        apply_to_addons = getattr(promo_group, 'apply_discounts_to_addons', True)
-        if apply_to_addons:
-            traffic_discount_percent = max(0, min(100, int(getattr(promo_group, 'traffic_discount_percent', 0) or 0)))
+    # Lock user BEFORE price computation to prevent TOCTOU on promo discount
+    from app.database.crud.user import lock_user_for_pricing
 
-    if traffic_discount_percent > 0:
-        base_price_kopeks = int(base_price_kopeks * (100 - traffic_discount_percent) / 100)
+    user = await lock_user_for_pricing(db, user.id)
+
+    # Применяем скидку промогруппы на трафик через PricingEngine
+    from app.services.pricing_engine import pricing_engine
+
+    base_price_kopeks, _discount_val, traffic_discount_percent = pricing_engine.calculate_traffic_discount(
+        base_price_kopeks,
+        user,
+    )
 
     # Пропорциональный расчет цены с учетом оставшегося времени подписки
     final_price, days_charged = calculate_prorated_price(
@@ -7280,7 +7133,21 @@ async def toggle_daily_subscription_pause_endpoint(
         new_paused_state = not is_currently_paused
     subscription.is_daily_paused = new_paused_state
 
-    daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+    raw_daily_price = getattr(tariff, 'daily_price_kopeks', 0)
+
+    # Lock user BEFORE price computation to prevent TOCTOU on promo discount
+    from app.database.crud.user import lock_user_for_pricing
+
+    user = await lock_user_for_pricing(db, user.id)
+
+    # Apply group discount to daily price (consistent with DailySubscriptionService and resume-after-topup)
+    from app.services.pricing_engine import PricingEngine
+
+    promo_group = PricingEngine.resolve_promo_group(user)
+    daily_group_pct = promo_group.get_discount_percent('period', 1) if promo_group else 0
+    daily_price = (
+        PricingEngine.apply_discount(raw_daily_price, daily_group_pct) if daily_group_pct > 0 else raw_daily_price
+    )
 
     # Если снимаем с паузы, проверяем баланс и списываем оплату
     if not new_paused_state:

docs/project_structure_reference.md

@@ -127,7 +127,7 @@
   Функции: нет
 - `app/database/crud/subscription.py` — Python-модуль
   Классы: нет
-  Функции: `_get_discount_percent`
+  Функции: нет (ранее `_get_discount_percent` — удалена при консолидации в PricingEngine; см. `PricingEngine.resolve_promo_group()` и `PromoGroup.get_discount_percent()`)
 - `app/database/crud/subscription_conversion.py` — Python-модуль
   Классы: нет
   Функции: нет

tests/test_pricing_engine.py

@@ -265,6 +265,7 @@ class TestCalculateRenewalPriceTariffMode:
         subscription.purchased_traffic_gb = 0
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_offer_discount_percent = 0
         user.promo_offer_expires_at = None
         with (
@@ -293,6 +294,7 @@ class TestCalculateRenewalPriceTariffMode:
         subscription.purchased_traffic_gb = 0
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_offer_discount_percent = 0
         user.promo_offer_expires_at = None
         with (
@@ -319,6 +321,7 @@ class TestCalculateRenewalPriceTariffMode:
         subscription.device_limit = 4  # 2 extra devices
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         with (
             patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
             patch('app.services.pricing_engine.settings') as ms,
@@ -344,13 +347,14 @@ class TestCalculateRenewalPriceTariffMode:
         promo_group.get_discount_percent.return_value = 10
         user = MagicMock()
         user.promo_group = promo_group
+        user.get_primary_promo_group.return_value = promo_group
         with (
             patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=5),
             patch('app.services.pricing_engine.settings') as ms,
         ):
             ms.PRICE_PER_DEVICE = 5000
             result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
-        assert result.base_price == 20000
+        assert result.base_price == 18000  # 20000 discounted by 10%
         assert result.promo_group_discount == 2000
         # After group: 18000, then 5% off 18000 = 900
         assert result.promo_offer_discount == 900
@@ -367,9 +371,12 @@ class TestCalculateRenewalPriceTariffMode:
         subscription.tariff.device_limit = 1
         subscription.tariff.device_price_kopeks = None
         subscription.tariff.id = 1
+        subscription.tariff.is_daily = False
+        subscription.tariff.can_purchase_custom_days.return_value = False
         subscription.device_limit = 1
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         with (
             patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
             patch('app.services.pricing_engine.settings') as ms,
@@ -395,6 +402,7 @@ class TestCalculateRenewalPriceTariffMode:
         sub.device_limit = 2  # less than tariff's 5
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
 
         with patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0):
             result = await engine.calculate_renewal_price(db, sub, 30, user=user)
@@ -441,6 +449,7 @@ class TestCalculateRenewalPriceClassicMode:
         subscription.device_limit = 2
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_group_id = None
         user.promo_offer_discount_percent = 0
         user.promo_offer_expires_at = None
@@ -479,6 +488,7 @@ class TestCalculateRenewalPriceClassicMode:
         promo_group.get_discount_percent.return_value = 20
         user = MagicMock()
         user.promo_group = promo_group
+        user.get_primary_promo_group.return_value = promo_group
         user.promo_group_id = 1
         user.promo_offer_discount_percent = 10
         user.promo_offer_expires_at = None
@@ -511,6 +521,7 @@ class TestCalculateRenewalPriceClassicMode:
         subscription.device_limit = 1
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_group_id = None
         with (
             patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
@@ -539,6 +550,7 @@ class TestCalculateRenewalPriceClassicMode:
         subscription.device_limit = 5
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_group_id = None
         with (
             patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
@@ -569,6 +581,7 @@ class TestCalculateRenewalPriceClassicMode:
         subscription.device_limit = 1
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_group_id = None
         s1 = _make_server(price_kopeks=5000, server_id=10, squad_uuid='uuid-found')
         s3 = _make_server(price_kopeks=3000, server_id=30, squad_uuid='uuid-found2')
@@ -610,6 +623,7 @@ class TestCalculateRenewalPriceClassicMode:
         subscription.device_limit = 1
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_group_id = None
         with (
             patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
@@ -640,6 +654,7 @@ class TestCalculateRenewalPriceClassicMode:
         subscription.device_limit = 1
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_group_id = None
         with (
             patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
@@ -669,6 +684,7 @@ class TestCalculateRenewalPriceClassicMode:
         sub.device_limit = 1
         user = MagicMock()
         user.promo_group = None
+        user.get_primary_promo_group.return_value = None
         user.promo_group_id = None
 
         server = _make_server(price_kopeks=3000, squad_uuid='uuid-s1')
@@ -717,6 +733,7 @@ class TestCalculateRenewalPriceClassicMode:
 
         promo_group.get_discount_percent = MagicMock(side_effect=discount_by_category)
         user.promo_group = promo_group
+        user.get_primary_promo_group.return_value = promo_group
         user.promo_group_id = 1
 
         server = _make_server(price_kopeks=6000, squad_uuid='uuid-s1')
@@ -898,6 +915,7 @@ class TestOriginalPriceIdentity:
         promo_group = MagicMock()
         promo_group.get_discount_percent = MagicMock(return_value=25)
         user.promo_group = promo_group
+        user.get_primary_promo_group.return_value = promo_group
 
         with patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=15):
             result = await engine.calculate_renewal_price(db, sub, 30, user=user)
@@ -922,6 +940,7 @@ class TestOriginalPriceIdentity:
         promo_group = MagicMock()
         promo_group.get_discount_percent = MagicMock(return_value=20)
         user.promo_group = promo_group
+        user.get_primary_promo_group.return_value = promo_group
         user.promo_group_id = 1
 
         server = _make_server(price_kopeks=4000, squad_uuid='uuid-s1')
@@ -965,6 +984,9 @@ class TestOriginalPriceIdentity:
         promo_group = MagicMock()
         promo_group.get_discount_percent = MagicMock(return_value=10)
         user.promo_group = promo_group
+        user.get_primary_promo_group.return_value = promo_group
+        sub.tariff.is_daily = False
+        sub.tariff.can_purchase_custom_days.return_value = False
         with patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=5):
             result = await engine.calculate_renewal_price(db, sub, 30, user=user)
         assert result.original_total == 20000  # undiscounted subtotal